Clear Linux or Mac System Logs

Executive Summary

Clear Linux or Mac System Logs (T1685.006) is a MITRE ATT&CK technique associated with Defense Impairment. Adversaries may clear system logs to hide evidence of an intrusion.

Why Attackers Use It

Attackers use Clear Linux or Mac System Logs because it provides a reliable way to advance their objective within the Defense Impairment tactic, often with a favorable balance of impact versus detectability on Linux, macOS environments. Defenders should assess this behavior in the context of the affected platform and adjacent activity rather than treating it as a standalone indicator.

MITRE Description

Adversaries may clear system logs to hide evidence of an intrusion. macOS and Linux both keep track of system or user-initiated actions via system logs. The majority of native system logging is stored under the /var/log/ directory. Subfolders in this directory categorize logs by their related functions, such as:(Citation: Linux Logs)

• /var/log/messages:: General and system-related messages
• /var/log/secure or /var/log/auth.log: Authentication logs
• /var/log/utmp or /var/log/wtmp: Login records
• /var/log/kern.log: Kernel logs
• /var/log/cron.log: Crond logs
• /var/log/maillog: Mail server logs
• /var/log/httpd/: Web server access and error logs

Attack Flow

1. Attacker gains the prerequisite access or context described below.
2. Attacker executes Clear Linux or Mac System Logs to achieve its tactical objective (Defense Impairment).
3. Resulting access/data/effect is leveraged to advance the broader attack chain (see Related Techniques).

Prerequisites

• Platform(s): Linux, macOS
• ATT&CK does not define one universal permission requirement for this technique. Establish the required access from the observed implementation and affected platform.

Common Tools

• Tool attribution is implementation-specific. Use ATT&CK procedure examples and local telemetry to identify the binaries, services, scripts, accounts, or cloud resources involved.

Commands

No universal command represents Clear Linux or Mac System Logs. Capture the exact command line, arguments, parent process, account, host, and execution time from the investigated environment; do not operationalize unverified examples.

Network Traffic

• Network observability is implementation-dependent. Review DNS, proxy, firewall, flow, authentication, and packet telemetry around the activity window, then correlate remote endpoints and protocol behavior with host evidence.

Windows Events

Sysmon Events

Detection Opportunities

No MITRE detection guidance published for this technique.

Relevant ATT&CK Data Sources: N/A

Sigma Rules

A universal Sigma rule would create unreliable results because this technique has no single guaranteed observable. Build detection logic from a documented behavior and supported data source, scope it to the affected platform, and validate it against benign administrative activity before deployment.

Splunk Queries

Start with the data sources named in the detection section. Scope searches by asset, identity, and time window; correlate the primary behavior with preceding access and subsequent actions. A portable query is intentionally not provided where the technique lacks a universal schema or observable.

Investigation Workflow

1. Confirm that the observed behavior is consistent with Clear Linux or Mac System Logs and rule out expected administrative or application activity.
2. Establish the first-seen time, initiating identity, source system, target system, and affected resources.
3. Collect relevant host, identity, network, cloud, and application telemetry for the surrounding time window.
4. Correlate parent and child activity, remote connections, file or configuration changes, and related ATT&CK techniques.
5. Determine scope by searching for the same observable across peer assets and identities.
6. Preserve volatile evidence and record confidence, assumptions, and telemetry gaps before containment.

Containment

1. Isolate affected host(s)/account(s) identified during investigation.
2. Revoke or rotate any credentials/tokens potentially exposed.
3. Apply the mitigations listed below where not already enforced.
4. Validate no related techniques (see Related Techniques) were chained against the same asset.

Mitigation

• M1022 -- Restrict File and Directory Permissions: Restricting file and directory permissions involves setting access controls at the file system level to limit which users, groups, or processes can read, write, or execute files.
• M1029 -- Remote Data Storage: Remote Data Storage focuses on moving critical data, such as security logs and sensitive files, to secure, off-host locations to minimize unauthorized access, tampering, or destruction by adversaries.
• M1041 -- Encrypt Sensitive Information: Protect sensitive information at rest, in transit, and during processing by using strong encryption algorithms.

Related Techniques

• T1021.004
• T1057
• T1059.004
• T1070.004
• T1070.006
• T1140
• T1190
• T1685