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Potential Shadow File Read via Command Line Utilities

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Potential Shadow File Read via Command Line Utilities

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Identifies access to the /etc/shadow file via the commandline using standard system utilities. After elevating privileges to root, threat actors may attempt to read or dump this file in order to gain valid credentials. They may utilize these to move laterally undetected and access additional resources.

Rule type: eql

Rule indices:

auditbeat-*
logs-endpoint.events.*

Severity: medium

Risk score: 47

Runs every: 5 minutes

Searches indices from: now-9m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References:

https://www.cyberciti.biz/faq/unix-linux-password-cracking-john-the-ripper/

Tags:

Elastic
Host
Linux
Threat Detection
Privilege Escalation
Credential Access

Version: 2 (version history)

Added (Elastic Stack release): 8.5.0

Last modified (Elastic Stack release): 8.6.0

Rule authors: Elastic

Rule license: Elastic License v2

Rule query

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process where event.type == "start" and event.action == "exec" and
user.name == "root" and (process.args : "/etc/shadow" or
(process.working_directory: "/etc" and process.args: "shadow")) and
not process.executable: ("/usr/bin/tar", "/bin/tar",
"/usr/bin/gzip", "/bin/gzip", "/usr/bin/zip",
"/bin/zip", "/usr/bin/stat", "/bin/stat",
"/usr/bin/cmp", "/bin/cmp", "/usr/bin/sudo",
"/bin/sudo", "/usr/bin/find", "/bin/find",
"/usr/bin/ls", "/bin/ls", "/usr/bin/uniq", "/bin/uniq",
"/usr/bin/unzip", "/bin/unzip") and not
process.parent.executable: "/bin/dracut"

Threat mapping

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Framework: MITRE ATT&CK^TM

Tactic:
- Name: Privilege Escalation
- ID: TA0004
- Reference URL: https://attack.mitre.org/tactics/TA0004/
Technique:
- Name: Exploitation for Privilege Escalation
- ID: T1068
- Reference URL: https://attack.mitre.org/techniques/T1068/
Tactic:
- Name: Credential Access
- ID: TA0006
- Reference URL: https://attack.mitre.org/tactics/TA0006/
Technique:
- Name: OS Credential Dumping
- ID: T1003
- Reference URL: https://attack.mitre.org/techniques/T1003/

Rule version history

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Version 2 (8.6.0 release)

Rule name changed from: Shadow File Read via Command Line Utilities

Updated query, changed from:

process where event.type == "start" and event.action == "exec" and
user.name == "root" and process.args : "/etc/shadow" and not
process.executable: ("/usr/bin/find", "/usr/bin/cmp", "/bin/ls",
"/usr/sbin/restorecon", "/usr/bin/uniq") and not
process.parent.executable: "/bin/dracut"

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