Potential Backdoor Execution Through PAM_EXEC
editPotential Backdoor Execution Through PAM_EXEC
editThis rule detects SSH session ID change followed by a suspicious SSHD child process, this may indicate the successful execution of a potentially malicious process through the Pluggable Authentication Module (PAM) utility. PAM is a framework used by Linux systems to authenticate users. Adversaries may create malicious PAM modules that grant them persistence onto the target every time a user logs in by executing a backdoor script or command.
Rule type: eql
Rule indices:
- logs-endpoint.events.process*
Severity: medium
Risk score: 47
Runs every: 5m
Searches indices from: now-9m (Date Math format, see also Additional look-back time)
Maximum alerts per execution: 100
References:
Tags:
- Domain: Endpoint
- OS: Linux
- Use Case: Threat Detection
- Tactic: Credential Access
- Tactic: Persistence
- Data Source: Elastic Defend
Version: 1
Rule authors:
- Elastic
Rule license: Elastic License v2
Rule query
editsequence by process.entity_id with maxspan=3s
[process where host.os.type == "linux" and event.type == "change" and event.action == "session_id_change" and process.name in ("ssh", "sshd")]
[process where host.os.type == "linux" and event.type == "start" and event.action == "exec" and process.parent.name in ("ssh", "sshd") and
process.args_count == 2 and (
process.name like ("perl*", "python*", "php*", "ruby*", "lua*") or
process.executable like (
"/tmp/*", "/var/tmp/*", "/dev/shm/*", "./*", "/boot/*", "/sys/*", "/lost+found/*", "/media/*", "/proc/*",
"/var/backups/*", "/var/log/*", "/var/mail/*", "/var/spool/*") or
process.name like ".*"
)]
Framework: MITRE ATT&CKTM
-
Tactic:
- Name: Persistence
- ID: TA0003
- Reference URL: https://attack.mitre.org/tactics/TA0003/
-
Technique:
- Name: Create or Modify System Process
- ID: T1543
- Reference URL: https://attack.mitre.org/techniques/T1543/
-
Tactic:
- Name: Credential Access
- ID: TA0006
- Reference URL: https://attack.mitre.org/tactics/TA0006/
-
Technique:
- Name: Modify Authentication Process
- ID: T1556
- Reference URL: https://attack.mitre.org/techniques/T1556/