Elastic Security Detection Rules

Suspicious Passwd File Event Action

Last updated 4 months ago on 2025-02-04
Created a year ago on 2024-01-22

About

Monitors for the generation of a passwd password entry via openssl, followed by a file write activity on the "/etc/passwd" file. The "/etc/passwd" file in Linux stores user account information, including usernames, user IDs, group IDs, home directories, and default shell paths. Attackers may exploit a misconfiguration in the "/etc/passwd" file permissions or other privileges to add a new entry to the "/etc/passwd" file with root permissions, and leverage this new user account to login as root.
Tags
Data Source: Auditd ManagerDomain: EndpointOS: LinuxUse Case: Threat DetectionTactic: Privilege EscalationData Source: Elastic DefendLanguage: eql
Severity
medium
Risk Score
47
MITRE ATT&CK™

Privilege Escalation (TA0004)(opens in a new tab or window)

↳ Exploitation for Privilege Escalation (T1068)(opens in a new tab or window)

License
Elastic License v2(opens in a new tab or window)

Definition

Rule Type
Event Correlation Rule
Integration Pack
Prebuilt Security Detection Rules
Index Patterns
logs-auditd_manager.auditd-*logs-endpoint.events.file*logs-endpoint.events.process*
Related Integrations

endpoint(opens in a new tab or window)

auditd_manager(opens in a new tab or window)

Query
sequence by host.id, process.parent.pid with maxspan=1m
  [process where host.os.type == "linux" and event.type == "start" and event.action == "exec" and
   process.name == "openssl" and process.args == "passwd" and user.id != "0"]
  [file where host.os.type == "linux" and file.path == "/etc/passwd" and process.parent.pid != 1 and
   not auditd.data.a2 == "80000" and event.outcome == "success" and user.id != "0"]

Install detection rules in Elastic Security

Detect Suspicious Passwd File Event Action in the Elastic Security detection engine by installing this rule into your Elastic Stack.

To setup this rule, check out the installation guide for Prebuilt Security Detection Rules(opens in a new tab or window).