Adobe Hijack Persistence

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Detects writing executable files that will be automatically launched by Adobe on launch.

Rule type: eql

Rule indices:

  • winlogbeat-*
  • logs-endpoint.events.*
  • logs-windows.*

Severity: low

Risk score: 21

Runs every: 5 minutes

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

Maximum alerts per execution: 100

References:

Tags:

  • Elastic
  • Host
  • Windows
  • Threat Detection
  • Persistence

Version: 10 (version history)

Added (Elastic Stack release): 7.6.0

Last modified (Elastic Stack release): 8.2.0

Rule authors: Elastic

Rule license: Elastic License v2

Investigation guide

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## Triage and analysis

### Investigating Adobe Hijack Persistence

Attackers can replace the `RdrCEF.exe` executable with their own to maintain their access, which will be launched
whenever Adobe Acrobat Reader is executed.

#### Possible investigation steps

- Investigate the process execution chain (parent process tree).
- Identify the user account that performed the action.
- Investigate other alerts associated with the user/host during the past 48 hours.
- Check for similar behavior in other hosts on the environment.
- Retrieve the file and determine if it is malicious:
  - Use a private sandboxed malware analysis system to perform analysis.
    - Observe and collect information about the following activities:
      - Attempts to contact external domains and addresses.
      - File and registry access, modification, and creation activities.
      - Service creation and launch activities.
      - Scheduled tasks creation.
  - Use the PowerShell Get-FileHash cmdlet to get the SHA-256 hash value of the file.
    - Search for the existence and reputation of this file in resources like VirusTotal, Hybrid-Analysis, CISCO Talos, Any.run, etc.

### False positive analysis

- This activity is unlikely to happen legitimately. Benign true positives (B-TPs) can be added as exceptions if necessary.

### Response and remediation

- Initiate the incident response process based on the outcome of the triage.
- Isolate the involved host to prevent further post-compromise behavior.
- If the triage identified malware, search the environment for additional compromised hosts.
  - Implement any temporary network rules, procedures, and segmentation required to contain the malware.
  - Immediately block the IoCs identified.
- Remove and block malicious artifacts identified on the triage.
- Disable the involved accounts, or restrict their ability to log on remotely.
- Reset passwords for the user account and other potentially compromised accounts (email, services, CRMs, etc.).


## Config

If enabling an EQL rule on a non-elastic-agent index (such as beats) for versions <8.2, events will not define `event.ingested` and default fallback for EQL rules was not added until 8.2, so you will need to add a custom pipeline to populate `event.ingested` to @timestamp for this rule to work.

Rule query

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file where event.type == "creation" and file.path : ("?:\\Program
Files (x86)\\Adobe\\Acrobat Reader DC\\Reader\\AcroCEF\\RdrCEF.exe",
"?:\\Program Files\\Adobe\\Acrobat Reader
DC\\Reader\\AcroCEF\\RdrCEF.exe") and not process.name :
"msiexec.exe"

Threat mapping

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Framework: MITRE ATT&CKTM

Rule version history

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Version 10 (8.2.0 release)
  • Formatting only
Version 9 (7.13.0 release)
  • Updated query, changed from:

    event.category:file and event.type:creation and file.path:("C:\Program
    Files (x86)\Adobe\Acrobat Reader DC\Reader\AcroCEF\RdrCEF.exe" or
    "C:\Program Files\Adobe\Acrobat Reader DC\Reader\AcroCEF\RdrCEF.exe")
    and not process.name:msiexec.exe
Version 8 (7.12.0 release)
  • Formatting only
Version 7 (7.11.2 release)
  • Formatting only
Version 6 (7.11.0 release)
  • Formatting only
Version 5 (7.10.0 release)
  • Formatting only
Version 4 (7.9.1 release)
  • Formatting only
Version 3 (7.9.0 release)
  • Updated query, changed from:

    file.path:("C:\Program Files (x86)\Adobe\Acrobat Reader
    DC\Reader\AcroCEF\RdrCEF.exe" or "C:\Program Files\Adobe\Acrobat
    Reader DC\Reader\AcroCEF\RdrCEF.exe") and event.action:"File created
    (rule: FileCreate)" and not process.name:msiexec.exe
Version 2 (7.6.2 release)
  • Updated query, changed from:

    file.path:("C:\Program Files (x86)\Adobe\Acrobat Reader
    DC\Reader\AcroCEF\RdrCEF.exe" or "C:\Program Files\Adobe\Acrobat
    Reader DC\Reader\AcroCEF\RdrCEF.exe") and event.action:"File created
    (rule: FileCreate)" and not process.name:msiexeec.exe