IMPORTANT: No additional bug fixes or documentation updates will be released for this version. For the latest information, see the current release documentation.

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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: 5m

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: 4

Rule authors:

Elastic

Rule license: Elastic License v2

Rule query

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process where host.os.type == "linux" and 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",
    "/usr/sbin/restorecon",
    "/sbin/restorecon")
  and not process.parent.executable: "/bin/dracut" and
  not (process.executable : ("/bin/chown", "/usr/bin/chown") and process.args : "root:shadow") and
  not (process.executable : ("/bin/chmod", "/usr/bin/chmod") and process.args : "640")

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/
Sub-technique:
- Name: /etc/passwd and /etc/shadow
- ID: T1003.008
- Reference URL: https://attack.mitre.org/techniques/T1003/008/

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