Detect Clear Linux or Mac System Logs in Elastic Security
Adversaries clear system logs on Linux and macOS to remove evidence of intrusion. Primary targets include /var/log/auth.log or /var/log/secure (authentication), /var/log/syslog or /var/log/messages (general), /var/log/wtmp and /var/log/btmp (login records), and web server logs (/var/log/apache2/, /var/log/nginx/). Common methods include truncating files (echo > /var/log/auth.log), deletion (rm /var/log/*.log), or overwriting with zeros. TeamTNT (crypto-mining), Rocke, Sea Turtle (DNS hijacking), Salt Typhoon (telecom espionage), UPSTYLE (Volt Typhoon PANW exploit), and MacMa (macOS) have all cleared Linux/macOS logs post-compromise.
MITRE ATT&CK
- Tactic
- Defense Evasion
- Technique
- T1070 Indicator Removal
- Sub-technique
- T1070.002 Clear Linux or Mac System Logs
- Canonical reference
- https://attack.mitre.org/techniques/T1070/002/
Elastic Detection Query
file where event.action in ("deletion", "overwrite", "truncation") and
(
file.path like~ "/var/log/*" or
file.path like~ "/Library/Logs/*" or
file.path like~ "/private/var/log/*"
) and
(
file.name like~ "*.log" or
file.name in~ ("auth.log", "syslog", "messages", "secure", "wtmp", "btmp", "lastlog", "kern.log")
) and
not process.name in ("logrotate", "newsyslog", "rsyslog", "syslogd", "aslmanager", "logger")Detects deletion, truncation, or overwriting of Linux and macOS system log files outside of legitimate log rotation processes. Covers /var/log/, /Library/Logs/, and /private/var/log/ paths targeting auth, syslog, wtmp, btmp, and kernel logs.
Data Sources
Required Tables
False Positives & Tuning
- Log rotation daemons (logrotate on Linux, newsyslog on macOS) that are not excluded by the process filter — verify process.name and parent context
- Security or observability agents (Elastic Agent, Filebeat, Splunk UF) that manage their own log files within monitored paths
- Container orchestration environments where ephemeral containers routinely delete log files on shutdown or cleanup
Other platforms for T1070.002
Testing Methodology
Validate this detection against 3 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.
- Test 1Clear Linux Auth Log via Truncation
Expected signal: auditd: SYSCALL records showing open with O_TRUNC flag on /var/log/auth.log. File modification event captured by endpoint telemetry. rsyslog may log a restart after the file is truncated if it monitors file size.
- Test 2Delete /var/log Files Using rm
Expected signal: auditd: SYSCALL records for creat/open (file creation) and unlink (file deletion). File creation and deletion events in endpoint telemetry. The file creation followed immediately by deletion pattern is anomalous.
- Test 3Clear Login History via wtmp Manipulation
Expected signal: auditd: SYSCALL for open with O_TRUNC on /var/log/wtmp. Any process monitoring wtmp (e.g., login daemons) may detect the size change. File modification event in endpoint telemetry for wtmp.
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