TLS/SSL: Transport Layer Security/Secure Socket Layer

encrypted layer 7 SSL TLS

Introduction

This tutorial discusses the plugin sslDecode. It extracts all relevant non-encrypted parameters useful for encrypted malware detection. Some commercial companies use this method as preprocessing for their AI detectors and sell that capability very expensive. Now you can do it as well.

Preparation

First, restore T2 into a pristine state by removing all unnecessary or older plugins from the plugin folder ~/.tranalyzer/plugins:

t2build -e -y

Are you sure you want to empty the plugin folder '/home/wurst/.tranalyzer/plugins' (y/N)? yes
Plugin folder emptied

Then compile the core (tranalyzer2) and the following plugins:

t2build tranalyzer2 basicFlow tcpStates sslDecode smtpDecode txtSink

...
BUILD SUCCESSFUL

If you did not create a separate data and results directory yet, please do it now in another bash window, that facilitates your workflow:

mkdir ~/data ~/results

The sample PCAP used in this tutorial can be downloaded here: faf-exercise.pcap.

Please save it in your ~/data folder.

Now you are all set for analyzing SSL/TLS traffic!

sslDecode

As we learnt in the smtpDecode tutorial, we have SSL/TLS traffic in our test pcap, I like you to have some correlation with the SSL output in the flow file later, so we load the smtpDecode plugin as well.

Let’s look at the plugin configuration first. You have the choice of printing anything what has value for the analyst. So extensions, coding, Certs, protocols, algorithms, etc. We leave everything as default.

sslDecode

vi src/sslDecode.h

...
/* ========================================================================== */
/* ------------------------ USER CONFIGURATION FLAGS ------------------------ */
/* ========================================================================== */

// OpenVPN
#define SSL_ANALYZE_OVPN       0 // analyze OpenVPN (Experimental)

// SSL/TLS
#define SSL_EXT_LIST           1 // output the list and number of extensions
#define SSL_MAX_EXT            8 // maximum number of extensions to store

#define SSL_EC                 1 // output the list and number of Elliptic Curve
#define SSL_MAX_EC             6 // maximum number of EC to store

#define SSL_EC_FORMATS         1 // output the list and number of Elliptic Curve point formats
#define SSL_MAX_EC_FORMATS     6 // maximum number of EC formats to store

#define SSL_PROTO_LIST         1 // output the list and number of protocols
#define SSL_MAX_PROTO          6 // maximum number of protocols to store
#define SSL_PROTO_LEN         16 // maximum number of characters per protocols

#define SSL_CIPHER_LIST        1 // output the list and number of supported ciphers
#define SSL_MAX_CIPHER        30 // maximum number of ciphers to store

#define SSL_ANALYZE_CERT       1 // analyze certificates

#if SSL_ANALYZE_CERT == 1

#define SSL_CERT_SERIAL        1 // print the certificate serial number
#define SSL_CERT_FINGPRINT     1 // 0: no certificate fingerprint, 1: SHA1, 2: MD5
#define SSL_CERT_VALIDITY      1 // print the certificate validity (Valid from/to)
#define SSL_CERT_SIG_ALG       1 // print the certificate signature algorithm
#define SSL_CERT_PUBKEY_ALG    1 // print the certificate public key algorithm
#define SSL_CERT_ALG_NAME_LONG 0 // use short (0) or long (1) names for algorithms
#define SSL_CERT_PUBKEY_TS     1 // print the certificate public key type and size

#define SSL_CERT_SUBJECT       2 // 0: no information about the certificate subject,
                                 // 1: print the whole subject as one string,
                                 // 2: print selected fields only
#define SSL_CERT_ISSUER        2 // 0: no information about the certificate issuer,
                                 // 1: print the whole issuer as one string,
                                 // 2: print selected fields only

#if ((SSL_CERT_SUBJECT == 2) || (SSL_CERT_ISSUER == 2))
#define SSL_CERT_COMMON_NAME   1 // print the common name of the issuer/subject
#define SSL_CERT_ORGANIZATION  1 // print the organization name of the issuer/subject
#define SSL_CERT_ORG_UNIT      1 // print the organizational unit name of the issuer/subject
#define SSL_CERT_LOCALITY      1 // print the locality name of the issuer/subject
#define SSL_CERT_STATE         1 // print the state or province of the issuer/subject
#define SSL_CERT_COUNTRY       1 // print the country of the issuer/subject
#endif // ((SSL_CERT_SUBJECT == 2) || (SSL_CERT_ISSUER == 2))

#if (SSL_CERT_VALIDITY == 1 && SSL_CERT_PUBKEY_TS == 1 && ( \
        (SSL_CERT_SUBJECT == 1 && SSL_CERT_ISSUER == 1)) || \
        (SSL_CERT_SUBJECT == 2 && SSL_CERT_ISSUER == 2 && SSL_CERT_COMMON_NAME == 1 && SSL_CERT_ORGANIZATION == 1))
#define SSL_DETECT_TOR         0 // print if TLS connection is likely a Tor one
#endif

// TODO in order to analyze ALL certificates, we need to reassemble packets...
#define SSL_SAVE_CERT          0 // save certificates
#define SSL_CERT_NAME_FINDEX   0 // prepend the flowIndex to the certificate name

#if SSL_SAVE_CERT == 1 || SSL_CERT_FINGPRINT == 1
#define SSL_BLIST              0 // Search for blacklisted certificates
#define SSL_BLIST_LEN         41 // Max length for blacklist descriptions
#define SSL_JA3                1 // Output JA3 fingerprint (hash and description)
#define SSL_JA3_STR            0 // Also output JA3 fingerprint before hashing
#define SSL_JA3_DLEN         512 // Max length for JA3 descriptions
#define SSL_JA3_STR_LEN     1024 // Max length for uncompressed JA3 signatures (ja3_str)

/* +++++++++++++++++++++ ENV / RUNTIME - conf Variables +++++++++++++++++++++ */

#define SSL_RM_CERTDIR      1                 // remove SSL_CERT_PATH before starting
#define SSL_CERT_PATH       "/tmp/TranCerts/" // folder for saved certificates
#define SSL_CERT_EXT        ".pem"            // extension for saved certificates
#endif // SSL_SAVE_CERT == 1 || SSL_CERT_FINGPRINT == 1

#endif // SSL_ANALYZE_CERT == 1

/* ========================================================================== */
/* ------------------------- DO NOT EDIT BELOW HERE ------------------------- */
/* ========================================================================== */
...

Now run t2 on the supplied pcap.

t2 -r ~/data/faf-exercise.pcap -w ~/results/

As expected there is SMTP and SSL traffic in the pcap, aka ESMTP. So what does the aggregated sslStat tells us?

tawk -V sslStat=0x2020

The sslStat column with value 0x2020 is to be interpreted as follows:

   bit | sslStat | Description
   =============================================================================
     5 | 0x0020  | Connection was renegotiated (existed before)
    13 | 0x2000  | Weak cipher detected (Null, DES, RC4 (RFC7465), ADH, 40/56 bits)

Oups, one of the partners decided to use a weak cipher, nice. Let’s extract all SSL flows. You see the ESMTP flows and if you position the slider more to the right the output of the sslDecode plugin.

If you look at the sslJA3Desc at the end, you will see all human readable description, which states nicely that it is a malware test. Did somebody attack the receiving host?

tawk 'bitsanyset($sslStat, 0xffff)' ~/results/faf-exercise_flows.txt | tcol

%dir  flowInd  flowStat            timeFirst          timeLast           duration  numHdrDesc  numHdrs  hdrDesc       srcMac             dstMac             ethType  ethVlanID  srcIP          srcIPCC  srcIPOrg           srcPort  dstIP          dstIPCC  dstIPOrg           dstPort  l4Proto  tcpStatesAFlags  smtpStat  smtpCC  smtpRC   smtpUsr  smtpPW  smtpSANum  smtpESANum  smtpERANum  smtpSA                                                                                                                                                          smtpESA  smtpERA  sslStat  sslProto  sslFlags  sslVersion  sslVuln  sslAlert    sslCipher  sslNumExt  sslExtList     sslNumECPt  sslECPt               sslNumECFormats  sslECFormats  sslNumProto  sslProtoList  sslNumCipher  sslCipherList                                                                        sslNumCC_A_H_AD_HB  sslSessIdLen  sslGMTTime         sslServerName  sslCertVersion  sslCertSerial  sslCertSha1FP                             sslCNotValidBefore_after_lifetime             sslCSigAlg  sslCKeyAlg       sslCPKeyType_Size  sslCSubjectCommonName  sslCSubjectOrgName  sslCSubjectOrgUnit  sslCSubjectLocality  sslCSubjectState  sslCSubjectCountry  sslCIssuerCommonName  sslCIssuerOrgName  sslCIssuerOrgUnit  sslCIssuerLocality  sslCIssuerState  sslCIssuerCountry  sslJA3Hash                        sslJA3Desc
B     12       0x0400000000004001  1258563573.941709  1258563576.594045  2.652336  1           3        eth:ipv4:tcp  00:19:e3:e7:5d:23  00:0b:db:63:5b:d4  0x0800              192.168.1.1    07       "Private network"  25       192.168.1.103  07       "Private network"  1397     6        0x08             0x01              220;250                   3          0           0           "220 domex ESMTP Postfix";"250-domex_250-PIPELINING_250-SIZE 10485760_250-VRFY_250-ETRN_250-AUTH L220 2.0.0 Ready to start TLS";"220 2.0.0 Ready to start TLS"                    0x2000   0x0000    0x00      0x0301      0x00     0x00000000  0x0004     0                         0                                 0                              0                          1             0x0004                                                                               1_0_4_8_0           32            1258563574.000000                 3               01             584728c5c136f59aa9ea3fa1befb735149f846a0  1254499973.000000_1286035973.000000_31536000  "RSA-SHA1"  "rsaEncryption"  RSA_2048           "domex.local"                                                                                         US                  "domex.local"                                                                                    US                 53611273a714cb4789c8222932efd5a7
A     13       0x0400000000004000  1258565030.304653  1258565030.420837  0.116184  1           3        eth:ipv4:tcp  00:0b:db:63:5b:d4  00:19:e3:e7:5d:23  0x0800              192.168.1.103  07       "Private network"  1749     192.168.1.1    07       "Private network"  25       6        0x00             0x01      EHLO                              1          0           0           "m57pat"                                                                                                                                                                          0x2020   0x0000    0x00      0x0301      0x00     0x00000000  0x0004     0                         0                                 0                              0                          11            0x0004;0x0005;0x000a;0x0009;0x0064;0x0062;0x0003;0x0006;0x0013;0x0012;0x0063         1_0_3_8_0           32            1258565252.000000                                                                                                                                                                                                                                                                                                                                                                                                                                      de350869b8c85de67a350c8d186f11e6  "Mozilla/4.0 (compatible; MSIE 6.0 or MSIE 7.0; Windows NT 5.2; SV1; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.04506.648; .NET CLR 3.5.21022), Malware Test FP: angler-ek-malware-payload-sandbox-analysis-winxp, smoke-loader-post-infection-traffic"
B     13       0x0400000000004001  1258565030.304696  1258565030.420877  0.116181  1           3        eth:ipv4:tcp  00:19:e3:e7:5d:23  00:0b:db:63:5b:d4  0x0800              192.168.1.1    07       "Private network"  25       192.168.1.103  07       "Private network"  1749     6        0x08             0x01              220;250                   3          0           0           "220 domex ESMTP Postfix";"250-domex_250-PIPELINING_250-SIZE 10485760_250-VRFY_250-ETRN_250-AUTH L220 2.0.0 Ready to start TLS";"220 2.0.0 Ready to start TLS"                    0x2000   0x0000    0x00      0x0301      0x00     0x00000000  0x0004     0                         0                                 0                              0                          1             0x0004                                                                               1_0_4_7_0           32            1258565030.000000                 3               01             584728c5c136f59aa9ea3fa1befb735149f846a0  1254499973.000000_1286035973.000000_31536000  "RSA-SHA1"  "rsaEncryption"  RSA_2048           "domex.local"                                                                                         US                  "domex.local"                                                                                    US                 53611273a714cb4789c8222932efd5a7
A     14       0x0400000000004000  1258565174.919134  1258565175.037809  0.118675  1           3        eth:ipv4:tcp  00:0b:db:63:5b:d4  00:19:e3:e7:5d:23  0x0800              192.168.1.103  07       "Private network"  1755     192.168.1.1    07       "Private network"  25       6        0x00             0x01      EHLO                              1          0           0           "m57pat"                                                                                                                                                                          0x2020   0x0000    0x00      0x0301      0x00     0x00000000  0x0004     0                         0                                 0                              0                          11            0x0004;0x0005;0x000a;0x0009;0x0064;0x0062;0x0003;0x0006;0x0013;0x0012;0x0063         1_0_3_8_0           32            1258565397.000000                                                                                                                                                                                                                                                                                                                                                                                                                                      de350869b8c85de67a350c8d186f11e6  "Mozilla/4.0 (compatible; MSIE 6.0 or MSIE 7.0; Windows NT 5.2; SV1; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.04506.648; .NET CLR 3.5.21022), Malware Test FP: angler-ek-malware-payload-sandbox-analysis-winxp, smoke-loader-post-infection-traffic"
B     14       0x0400000000004001  1258565174.919179  1258565175.037828  0.118649  1           3        eth:ipv4:tcp  00:19:e3:e7:5d:23  00:0b:db:63:5b:d4  0x0800              192.168.1.1    07       "Private network"  25       192.168.1.103  07       "Private network"  1755     6        0x08             0x01              220;250                   3          0           0           "220 domex ESMTP Postfix";"250-domex_250-PIPELINING_250-SIZE 10485760_250-VRFY_250-ETRN_250-AUTH L220 2.0.0 Ready to start TLS";"220 2.0.0 Ready to start TLS"                    0x2000   0x0000    0x00      0x0301      0x00     0x00000000  0x0004     0                         0                                 0                              0                          1             0x0004                                                                               1_0_4_7_0           32            1258565174.000000                 3               01             584728c5c136f59aa9ea3fa1befb735149f846a0  1254499973.000000_1286035973.000000_31536000  "RSA-SHA1"  "rsaEncryption"  RSA_2048           "domex.local"                                                                                         US                  "domex.local"                                                                                    US                 53611273a714cb4789c8222932efd5a7
A     15       0x0400000000004000  1258565820.302090  1258565821.898589  1.596499  1           3        eth:ipv4:tcp  00:08:74:38:01:b4  00:19:e3:e7:5d:23  0x0800              192.168.1.105  07       "Private network"  49218    192.168.1.1    07       "Private network"  25       6        0x00             0x01      EHLO                              1          0           0           "M57Terry"                                                                                                                                                                        0x2000   0x0000    0x00      0x0301      0x00     0x00000000  0x002f     2          0x000a;0x000b  3           0x0017;0x0018;0x0019  1                0x00          0                          12            0x002f;0x0035;0x0005;0x000a;0xc009;0xc00a;0xc013;0xc014;0x0032;0x0038;0x0013;0x0004  1_0_3_7_0           0             1258565965.000000                                                                                                                                                                                                                                                                                                                                                                                                                                      296c2c494ccfc5cb35d94bfbc74ef60a
A     16       0x0400000000004000  1258565880.189257  1258565880.212242  0.022985  1           3        eth:ipv4:tcp  00:08:74:38:01:b4  00:19:e3:e7:5d:23  0x0800              192.168.1.105  07       "Private network"  49219    192.168.1.1    07       "Private network"  25       6        0x00             0x01      EHLO                              1          0           0           "M57Terry"                                                                                                                                                                        0x2020   0x0000    0x00      0x0301      0x00     0x00000000  0x002f     2          0x000a;0x000b  3           0x0017;0x0018;0x0019  1                0x00          0                          12            0x002f;0x0035;0x0005;0x000a;0xc009;0xc00a;0xc013;0xc014;0x0032;0x0038;0x0013;0x0004  1_0_2_8_0           32            1258566025.000000                                                                                                                                                                                                                                                                                                                                                                                                                                      296c2c494ccfc5cb35d94bfbc74ef60a
A     17       0x0400000000004000  1258566050.124592  1258566050.238771  0.114179  1           3        eth:ipv4:tcp  00:08:74:38:01:b4  00:19:e3:e7:5d:23  0x0800              192.168.1.105  07       "Private network"  49220    192.168.1.1    07       "Private network"  25       6        0x00             0x01      EHLO                              1          0           0           "M57Terry"                                                                                                                                                                        0x2020   0x0000    0x00      0x0301      0x00     0x00000000  0x002f     2          0x000a;0x000b  3           0x0017;0x0018;0x0019  1                0x00          0                          12            0x002f;0x0035;0x0005;0x000a;0xc009;0xc00a;0xc013;0xc014;0x0032;0x0038;0x0013;0x0004  1_0_3_7_0           32            1258566195.000000                                                                                                                                                                                                                                                                                                                                                                                                                                      296c2c494ccfc5cb35d94bfbc74ef60a
A     18       0x0400000000004000  1258566123.706408  1258566123.739652  0.033244  1           3        eth:ipv4:tcp  00:0b:db:63:5b:d4  00:19:e3:e7:5d:23  0x0800              192.168.1.103  07       "Private network"  1806     192.168.1.1    07       "Private network"  25       6        0x00             0x01      EHLO                              1          0           0           "m57pat"                                                                                                                                                                          0x2020   0x0000    0x00      0x0301      0x00     0x00000000  0x0004     0                         0                                 0                              0                          11            0x0004;0x0005;0x000a;0x0009;0x0064;0x0062;0x0003;0x0006;0x0013;0x0012;0x0063         1_0_3_7_0           32            1258566346.000000                                                                                                                                                                                                                                                                                                                                                                                                                                      de350869b8c85de67a350c8d186f11e6  "Mozilla/4.0 (compatible; MSIE 6.0 or MSIE 7.0; Windows NT 5.2; SV1; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.04506.648; .NET CLR 3.5.21022), Malware Test FP: angler-ek-malware-payload-sandbox-analysis-winxp, smoke-loader-post-infection-traffic"
B     18       0x0400000000004001  1258566123.706462  1258566123.739692  0.033230  1           3        eth:ipv4:tcp  00:19:e3:e7:5d:23  00:0b:db:63:5b:d4  0x0800              192.168.1.1    07       "Private network"  25       192.168.1.103  07       "Private network"  1806     6        0x00             0x01              220;250                   3          0           0           "220 domex ESMTP Postfix";"250-domex_250-PIPELINING_250-SIZE 10485760_250-VRFY_250-ETRN_250-AUTH L220 2.0.0 Ready to start TLS";"220 2.0.0 Ready to start TLS"                    0x2000   0x0000    0x00      0x0301      0x00     0x00000000  0x0004     0                         0                                 0                              0                          1             0x0004                                                                               1_0_4_6_0           32            1258566123.000000                 3               01             584728c5c136f59aa9ea3fa1befb735149f846a0  1254499973.000000_1286035973.000000_31536000  "RSA-SHA1"  "rsaEncryption"  RSA_2048           "domex.local"                                                                                         US                  "domex.local"                                                                                    US                 53611273a714cb4789c8222932efd5a7
B     19       0x0400000000004001  1258567109.383558  1258567113.574642  4.191084  1           3        eth:ipv4:tcp  00:19:e3:e7:5d:23  00:0b:db:63:58:a6  0x0800              192.168.1.1    07       "Private network"  25       192.168.1.102  07       "Private network"  1400     6        0x08             0x01              220;250                   3          0           0           "220 domex ESMTP Postfix";"250-domex_250-PIPELINING_250-SIZE 10485760_250-VRFY_250-ETRN_250-AUTH L220 2.0.0 Ready to start TLS";"220 2.0.0 Ready to start TLS"                    0x2000   0x0000    0x00      0x0301      0x00     0x00000000  0x0004     0                         0                                 0                              0                          1             0x0004                                                                               1_0_4_6_0           32            1258567109.000000                 3               01             584728c5c136f59aa9ea3fa1befb735149f846a0  1254499973.000000_1286035973.000000_31536000  "RSA-SHA1"  "rsaEncryption"  RSA_2048           "domex.local"                                                                                         US                  "domex.local"                                                                                    US                 53611273a714cb4789c8222932efd5a7
A     20       0x0400000000004000  1258567248.261596  1258567248.374768  0.113172  1           3        eth:ipv4:tcp  00:0b:db:63:58:a6  00:19:e3:e7:5d:23  0x0800              192.168.1.102  07       "Private network"  1404     192.168.1.1    07       "Private network"  25       6        0x00             0x01      EHLO                              1          0           0           "m57jo"                                                                                                                                                                           0x2020   0x0000    0x00      0x0301      0x00     0x00000000  0x0004     0                         0                                 0                              0                          11            0x0004;0x0005;0x000a;0x0009;0x0064;0x0062;0x0003;0x0006;0x0013;0x0012;0x0063         1_0_3_7_0           32            1258567449.000000                                                                                                                                                                                                                                                                                                                                                                                                                                      de350869b8c85de67a350c8d186f11e6  "Mozilla/4.0 (compatible; MSIE 6.0 or MSIE 7.0; Windows NT 5.2; SV1; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.04506.648; .NET CLR 3.5.21022), Malware Test FP: angler-ek-malware-payload-sandbox-analysis-winxp, smoke-loader-post-infection-traffic"
B     20       0x0400000000004001  1258567248.261635  1258567248.374809  0.113174  1           3        eth:ipv4:tcp  00:19:e3:e7:5d:23  00:0b:db:63:58:a6  0x0800              192.168.1.1    07       "Private network"  25       192.168.1.102  07       "Private network"  1404     6        0x00             0x01              220;250                   3          0           0           "220 domex ESMTP Postfix";"250-domex_250-PIPELINING_250-SIZE 10485760_250-VRFY_250-ETRN_250-AUTH L220 2.0.0 Ready to start TLS";"220 2.0.0 Ready to start TLS"                    0x2000   0x0000    0x00      0x0301      0x00     0x00000000  0x0004     0                         0                                 0                              0                          1             0x0004                                                                               1_0_4_6_0           32            1258567248.000000                 3               01             584728c5c136f59aa9ea3fa1befb735149f846a0  1254499973.000000_1286035973.000000_31536000  "RSA-SHA1"  "rsaEncryption"  RSA_2048           "domex.local"                                                                                         US                  "domex.local"                                                                                    US                 53611273a714cb4789c8222932efd5a7
A     21       0x0400000000004000  1258567289.262109  1258567289.283592  0.021483  1           3        eth:ipv4:tcp  00:0b:db:63:58:a6  00:19:e3:e7:5d:23  0x0800              192.168.1.102  07       "Private network"  1405     192.168.1.1    07       "Private network"  25       6        0x00             0x01      EHLO                              1          0           0           "m57jo"                                                                                                                                                                           0x2020   0x0000    0x00      0x0301      0x00     0x00000000  0x0004     0                         0                                 0                              0                          11            0x0004;0x0005;0x000a;0x0009;0x0064;0x0062;0x0003;0x0006;0x0013;0x0012;0x0063         1_0_2_8_0           32            1258567490.000000                                                                                                                                                                                                                                                                                                                                                                                                                                      de350869b8c85de67a350c8d186f11e6  "Mozilla/4.0 (compatible; MSIE 6.0 or MSIE 7.0; Windows NT 5.2; SV1; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.04506.648; .NET CLR 3.5.21022), Malware Test FP: angler-ek-malware-payload-sandbox-analysis-winxp, smoke-loader-post-infection-traffic"
B     21       0x0400000000004001  1258567289.262156  1258567289.283642  0.021486  1           3        eth:ipv4:tcp  00:19:e3:e7:5d:23  00:0b:db:63:58:a6  0x0800              192.168.1.1    07       "Private network"  25       192.168.1.102  07       "Private network"  1405     6        0x00             0x01              220;250                   3          0           0           "220 domex ESMTP Postfix";"250-domex_250-PIPELINING_250-SIZE 10485760_250-VRFY_250-ETRN_250-AUTH L220 2.0.0 Ready to start TLS";"220 2.0.0 Ready to start TLS"                    0x2000   0x0000    0x00      0x0301      0x00     0x00000000  0x0004     0                         0                                 0                              0                          1             0x0004                                                                               1_0_2_7_0           32            1258567289.000000                                                                                                                                                                                                                                                                                                                                                                                                                                      53611273a714cb4789c8222932efd5a7
A     22       0x0400000000004000  1258567757.457759  1258567757.572930  0.115171  1           3        eth:ipv4:tcp  00:08:74:38:01:b4  00:19:e3:e7:5d:23  0x0800              192.168.1.105  07       "Private network"  49336    192.168.1.1    07       "Private network"  25       6        0x00             0x01      EHLO                              1          0           0           "M57Terry"                                                                                                                                                                        0x2020   0x0000    0x00      0x0301      0x00     0x00000000  0x002f     2          0x000a;0x000b  3           0x0017;0x0018;0x0019  1                0x00          0                          12            0x002f;0x0035;0x0005;0x000a;0xc009;0xc00a;0xc013;0xc014;0x0032;0x0038;0x0013;0x0004  1_0_3_7_0           32            1258567902.000000                                                                                                                                                                                                                                                                                                                                                                                                                                      296c2c494ccfc5cb35d94bfbc74ef60a
A     23       0x0400000000004000  1258568036.508358  1258568036.620287  0.111929  1           3        eth:ipv4:tcp  00:08:74:38:01:b4  00:19:e3:e7:5d:23  0x0800              192.168.1.105  07       "Private network"  49353    192.168.1.1    07       "Private network"  25       6        0x00             0x01      EHLO                              1          0           0           "M57Terry"                                                                                                                                                                        0x2020   0x0000    0x00      0x0301      0x00     0x00000000  0x002f     2          0x000a;0x000b  3           0x0017;0x0018;0x0019  1                0x00          0                          12            0x002f;0x0035;0x0005;0x000a;0xc009;0xc00a;0xc013;0xc014;0x0032;0x0038;0x0013;0x0004  1_0_3_7_0           32            1258568182.000000                                                                                                                                                                                                                                                                                                                                                                                                                                      296c2c494ccfc5cb35d94bfbc74ef60a
A     24       0x0400000000004000  1258568059.128662  1258568059.160656  0.031994  1           3        eth:ipv4:tcp  00:0b:db:63:5b:d4  00:19:e3:e7:5d:23  0x0800              192.168.1.103  07       "Private network"  1836     192.168.1.1    07       "Private network"  25       6        0x00             0x01      EHLO                              1          0           0           "m57pat"                                                                                                                                                                          0x2020   0x0000    0x00      0x0301      0x00     0x00000000  0x0004     0                         0                                 0                              0                          11            0x0004;0x0005;0x000a;0x0009;0x0064;0x0062;0x0003;0x0006;0x0013;0x0012;0x0063         1_0_3_7_0           32            1258568281.000000                                                                                                                                                                                                                                                                                                                                                                                                                                      de350869b8c85de67a350c8d186f11e6  "Mozilla/4.0 (compatible; MSIE 6.0 or MSIE 7.0; Windows NT 5.2; SV1; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.04506.648; .NET CLR 3.5.21022), Malware Test FP: angler-ek-malware-payload-sandbox-analysis-winxp, smoke-loader-post-infection-traffic"
B     24       0x0400000000004001  1258568059.128711  1258568059.160696  0.031985  1           3        eth:ipv4:tcp  00:19:e3:e7:5d:23  00:0b:db:63:5b:d4  0x0800              192.168.1.1    07       "Private network"  25       192.168.1.103  07       "Private network"  1836     6        0x00             0x01              220;250                   3          0           0           "220 domex ESMTP Postfix";"250-domex_250-PIPELINING_250-SIZE 10485760_250-VRFY_250-ETRN_250-AUTH L220 2.0.0 Ready to start TLS";"220 2.0.0 Ready to start TLS"                    0x2000   0x0000    0x00      0x0301      0x00     0x00000000  0x0004     0                         0                                 0                              0                          1             0x0004                                                                               1_0_4_6_0           32            1258568059.000000                 3               01             584728c5c136f59aa9ea3fa1befb735149f846a0  1254499973.000000_1286035973.000000_31536000  "RSA-SHA1"  "rsaEncryption"  RSA_2048           "domex.local"                                                                                         US                  "domex.local"                                                                                    US                 53611273a714cb4789c8222932efd5a7
A     25       0x0400000000004000  1258568667.549041  1258568667.662968  0.113927  1           3        eth:ipv4:tcp  00:0b:db:63:58:a6  00:19:e3:e7:5d:23  0x0800              192.168.1.102  07       "Private network"  1709     192.168.1.1    07       "Private network"  25       6        0x00             0x01      EHLO                              1          0           0           "m57jo"                                                                                                                                                                           0x2020   0x0000    0x00      0x0301      0x00     0x00000000  0x0004     0                         0                                 0                              0                          11            0x0004;0x0005;0x000a;0x0009;0x0064;0x0062;0x0003;0x0006;0x0013;0x0012;0x0063         1_0_3_7_0           32            1258568869.000000                                                                                                                                                                                                                                                                                                                                                                                                                                      de350869b8c85de67a350c8d186f11e6  "Mozilla/4.0 (compatible; MSIE 6.0 or MSIE 7.0; Windows NT 5.2; SV1; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.04506.648; .NET CLR 3.5.21022), Malware Test FP: angler-ek-malware-payload-sandbox-analysis-winxp, smoke-loader-post-infection-traffic"
B     25       0x0400000000004001  1258568667.549083  1258568667.662999  0.113916  1           3        eth:ipv4:tcp  00:19:e3:e7:5d:23  00:0b:db:63:58:a6  0x0800              192.168.1.1    07       "Private network"  25       192.168.1.102  07       "Private network"  1709     6        0x08             0x01              220;250                   3          0           0           "220 domex ESMTP Postfix";"250-domex_250-PIPELINING_250-SIZE 10485760_250-VRFY_250-ETRN_250-AUTH L220 2.0.0 Ready to start TLS";"220 2.0.0 Ready to start TLS"                    0x2000   0x0000    0x00      0x0301      0x00     0x00000000  0x0004     0                         0                                 0                              0                          1             0x0004                                                                               1_0_4_6_0           32            1258568667.000000                 3               01             584728c5c136f59aa9ea3fa1befb735149f846a0  1254499973.000000_1286035973.000000_31536000  "RSA-SHA1"  "rsaEncryption"  RSA_2048           "domex.local"                                                                                         US                  "domex.local"                                                                                    US                 53611273a714cb4789c8222932efd5a7
A     26       0x0400000000004000  1258568738.108255  1258568738.141234  0.032979  1           3        eth:ipv4:tcp  00:08:74:38:01:b4  00:19:e3:e7:5d:23  0x0800              192.168.1.105  07       "Private network"  49561    192.168.1.1    07       "Private network"  25       6        0x00             0x01      EHLO                              1          0           0           "M57Terry"                                                                                                                                                                        0x2020   0x0000    0x00      0x0301      0x00     0x00000000  0x002f     2          0x000a;0x000b  3           0x0017;0x0018;0x0019  1                0x00          0                          12            0x002f;0x0035;0x0005;0x000a;0xc009;0xc00a;0xc013;0xc014;0x0032;0x0038;0x0013;0x0004  1_0_3_7_0           32            1258568883.000000                                                                                                                                                                                                                                                                                                                                                                                                                                      296c2c494ccfc5cb35d94bfbc74ef60a
A     30       0x0400000000004000  1258581757.587843  1258581758.358872  0.771029  1           3        eth:ipv4:tcp  00:0b:db:63:5b:d4  00:19:e3:e7:5d:23  0x0800              192.168.1.103  07       "Private network"  1934     192.168.1.1    07       "Private network"  25       6        0x00             0x01      EHLO                              1          0           0           "m57pat"                                                                                                                                                                          0x2020   0x0000    0x00      0x0301      0x00     0x00000000  0x0004     0                         0                                 0                              0                          11            0x0004;0x0005;0x000a;0x0009;0x0064;0x0062;0x0003;0x0006;0x0013;0x0012;0x0063         1_0_3_7_0           32            1258581981.000000                                                                                                                                                                                                                                                                                                                                                                                                                                      de350869b8c85de67a350c8d186f11e6  "Mozilla/4.0 (compatible; MSIE 6.0 or MSIE 7.0; Windows NT 5.2; SV1; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.04506.648; .NET CLR 3.5.21022), Malware Test FP: angler-ek-malware-payload-sandbox-analysis-winxp, smoke-loader-post-infection-traffic"
B     30       0x0400000000004001  1258581757.587891  1258581758.358901  0.771010  1           3        eth:ipv4:tcp  00:19:e3:e7:5d:23  00:0b:db:63:5b:d4  0x0800              192.168.1.1    07       "Private network"  25       192.168.1.103  07       "Private network"  1934     6        0x08             0x01              220;250                   3          0           0           "220 domex ESMTP Postfix";"250-domex_250-PIPELINING_250-SIZE 10485760_250-VRFY_250-ETRN_250-AUTH L220 2.0.0 Ready to start TLS";"220 2.0.0 Ready to start TLS"                    0x2000   0x0000    0x00      0x0301      0x00     0x00000000  0x0004     0                         0                                 0                              0                          1             0x0004                                                                               1_0_4_6_0           32            1258581758.000000                 3               01             584728c5c136f59aa9ea3fa1befb735149f846a0  1254499973.000000_1286035973.000000_31536000  "RSA-SHA1"  "rsaEncryption"  RSA_2048           "domex.local"                                                                                         US                  "domex.local"                                                                                    US                 53611273a714cb4789c8222932efd5a7
A     31       0x0400000000004000  1258582107.588230  1258582108.822693  1.234463  1           3        eth:ipv4:tcp  00:0b:db:63:5b:d4  00:19:e3:e7:5d:23  0x0800              192.168.1.103  07       "Private network"  2008     192.168.1.1    07       "Private network"  25       6        0x00             0x01      EHLO                              1          0           0           "m57pat"                                                                                                                                                                          0x2020   0x0000    0x00      0x0301      0x00     0x00000000  0x0004     0                         0                                 0                              0                          11            0x0004;0x0005;0x000a;0x0009;0x0064;0x0062;0x0003;0x0006;0x0013;0x0012;0x0063         1_0_3_7_0           32            1258582331.000000                                                                                                                                                                                                                                                                                                                                                                                                                                      de350869b8c85de67a350c8d186f11e6  "Mozilla/4.0 (compatible; MSIE 6.0 or MSIE 7.0; Windows NT 5.2; SV1; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.04506.648; .NET CLR 3.5.21022), Malware Test FP: angler-ek-malware-payload-sandbox-analysis-winxp, smoke-loader-post-infection-traffic"
B     31       0x0400000000004001  1258582107.588266  1258582108.822724  1.234458  1           3        eth:ipv4:tcp  00:19:e3:e7:5d:23  00:0b:db:63:5b:d4  0x0800              192.168.1.1    07       "Private network"  25       192.168.1.103  07       "Private network"  2008     6        0x08             0x01              220;250                   3          0           0           "220 domex ESMTP Postfix";"250-domex_250-PIPELINING_250-SIZE 10485760_250-VRFY_250-ETRN_250-AUTH L220 2.0.0 Ready to start TLS";"220 2.0.0 Ready to start TLS"                    0x2000   0x0000    0x00      0x0301      0x00     0x00000000  0x0004     0                         0                                 0                              0                          1             0x0004                                                                               1_0_4_6_0           32            1258582108.000000                 3               01             584728c5c136f59aa9ea3fa1befb735149f846a0  1254499973.000000_1286035973.000000_31536000  "RSA-SHA1"  "rsaEncryption"  RSA_2048           "domex.local"                                                                                         US                  "domex.local"                                                                                    US                 53611273a714cb4789c8222932efd5a7
A     32       0x0400000000004000  1258583614.298059  1258583615.323171  1.025112  1           3        eth:ipv4:tcp  00:0b:db:63:58:a6  00:19:e3:e7:5d:23  0x0800              192.168.1.102  07       "Private network"  1911     192.168.1.1    07       "Private network"  25       6        0x00             0x01      EHLO                              1          0           0           "m57jo"                                                                                                                                                                           0x2020   0x0000    0x00      0x0301      0x00     0x00000000  0x0004     0                         0                                 0                              0                          11            0x0004;0x0005;0x000a;0x0009;0x0064;0x0062;0x0003;0x0006;0x0013;0x0012;0x0063         1_0_3_7_0           32            1258583817.000000                                                                                                                                                                                                                                                                                                                                                                                                                                      de350869b8c85de67a350c8d186f11e6  "Mozilla/4.0 (compatible; MSIE 6.0 or MSIE 7.0; Windows NT 5.2; SV1; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.04506.648; .NET CLR 3.5.21022), Malware Test FP: angler-ek-malware-payload-sandbox-analysis-winxp, smoke-loader-post-infection-traffic"
B     32       0x0400000000004001  1258583614.298161  1258583615.323218  1.025057  1           3        eth:ipv4:tcp  00:19:e3:e7:5d:23  00:0b:db:63:58:a6  0x0800              192.168.1.1    07       "Private network"  25       192.168.1.102  07       "Private network"  1911     6        0x08             0x01              220;250                   3          0           0           "220 domex ESMTP Postfix";"250-domex_250-PIPELINING_250-SIZE 10485760_250-VRFY_250-ETRN_250-AUTH L220 2.0.0 Ready to start TLS";"220 2.0.0 Ready to start TLS"                    0x2000   0x0000    0x00      0x0301      0x00     0x00000000  0x0004     0                         0                                 0                              0                          1             0x0004                                                                               1_0_4_6_0           32            1258583615.000000                 3               01             584728c5c136f59aa9ea3fa1befb735149f846a0  1254499973.000000_1286035973.000000_31536000  "RSA-SHA1"  "rsaEncryption"  RSA_2048           "domex.local"                                                                                         US                  "domex.local"

So the sslCipherList shows you all cyphers supported by the peers and the finally selected cypher 0x0004 which both peers support is weak, as a tawk shows below:

tawk -V sslCipher=0x0004

The sslCipher column with value 0x0004 is to be interpreted as follows:

   sslCipher | Description
   =============================================================================
      0x0004 | TLS_RSA_WITH_RC4_128_MD5 (WEAK)

If you need an explanation of the columns just look into the `faf-exercise_headers.txt* file:

# Col No.                               Type                                    Name                                    Description
...
34                                      S:R                                     smtpERA                                 SMTP Email receive addresses
35                                      H16                                     sslStat                                 SSL status
36                                      H16                                     sslProto                                SSL proto
37                                      H8                                      sslFlags                                SSL flags
38                                      H16                                     sslVersion                              SSL version
39                                      H8                                      sslVuln                                 SSL vulnerabilities
40                                      H32                                     sslAlert                                SSL alert
41                                      H16                                     sslCipher                               SSL preferred (Client) / negotiated (Server) cipher
42                                      U16                                     sslNumExt                               SSL number of extensions
43                                      H16:R                                   sslExtList                              SSL list of extensions
44                                      U16                                     sslNumECPt                              SSL number of EC points
45                                      H16:R                                   sslECPt                                 SSL list of EC points
46                                      U8                                      sslNumECFormats                         SSL number of EC point formats
47                                      H8:R                                    sslECFormats                            SSL list of EC point formats
48                                      U16                                     sslNumProto                             SSL number of protocols
49                                      S:R                                     sslProtoList                            SSL list of protocols
50                                      U16                                     sslNumCipher                            SSL number of supported ciphers
51                                      H16:R                                   sslCipherList                           SSL list of supported cipher
52                                      U16_U16_U16_U64_U64                     sslNumCC_A_H_AD_HB                      SSL number of change_cipher, alert, handshake, application data, heartbeat records
53                                      U8                                      sslSessIdLen                            SSL Session ID length
54                                      U64.U32:R                               sslGMTTime                              SSL GMT Unix Time
55                                      S:R                                     sslServerName                           SSL server name
56                                      U8:R                                    sslCertVersion                          SSL certificate version
57                                      SC:R                                    sslCertSerial                           SSL certificate serial number
58                                      SC:R                                    sslCertSha1FP                           SSL certificate SHA1 fingerprint
59                                      U64.U32_U64.U32_U64:R                   sslCNotValidBefore_after_lifetime       SSL certificate validity period (not valid before/after, lifetime (seconds))
60                                      S:R                                     sslCSigAlg                              SSL certificate signature algorithm
61                                      S:R                                     sslCKeyAlg                              SSL certificate public key algorithm
62                                      SC_U16:R                                sslCPKeyType_Size                       SSL certificate public key type, size (bits)
63                                      S:R                                     sslCSubjectCommonName                   SSL certificate subject common name
64                                      S:R                                     sslCSubjectOrgName                      SSL certificate subject organization name
65                                      S:R                                     sslCSubjectOrgUnit                      SSL certificate subject organizational unit name
66                                      S:R                                     sslCSubjectLocality                     SSL certificate subject locality name
67                                      S:R                                     sslCSubjectState                        SSL certificate subject state or province name
68                                      SC:R                                    sslCSubjectCountry                      SSL certificate subject country name
69                                      S:R                                     sslCIssuerCommonName                    SSL certificate issuer common name
70                                      S:R                                     sslCIssuerOrgName                       SSL certificate issuer organization name
71                                      S:R                                     sslCIssuerOrgUnit                       SSL certificate issuer organizational unit name
72                                      S:R                                     sslCIssuerLocality                      SSL certificate issuer locality name
73                                      S:R                                     sslCIssuerState                         SSL certificate issuer state or province name
74                                      SC:R                                    sslCIssuerCountry                       SSL certificate issuer country name
75                                      SC:R                                    sslJA3Hash                              SSL JA3 fingerprint
76                                      S:R                                     sslJA3Desc                              SSL JA3 description

Now is that an attack? Which plugin you might need now? Have a look into the Data carving with smtpDecode tutorial! I leave that exercise to you.

Conclusion

Don’t forget to reset the plugin configuration for the next tutorial.

t2conf sslDecode --reset && t2build sslDecode

Have fun analyzing.