Sigma rule: UNC4841 - Barracuda ESG Exploitation Indicators

A detection rule from the SigmaHQ repository, shown as its author published it. Dataset version ref-9eed07b12cb9, updated 2025-08-19T00:00:00.000Z.

Rule

Title
UNC4841 - Barracuda ESG Exploitation Indicators
Status
test
Level
high
Author
Nasreddine Bencherchali (Nextron Systems)
Date
2023-06-16
Modified
2025-08-19
File
rules-emerging-threats/2023/TA/UNC4841-Barracuda-ESG-Zero-Day-Exploitation/file_event_lnx_apt_unc4841_file_indicators.yml
Commit
ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects file indicators as seen used by UNC4841 during their Barracuda ESG zero day exploitation.

Log source

product
linux
category
file_event

Detection

selection:
    TargetFilename|endswith:
        - '/11111.tar'
        - '/aacore.sh'
        - '/appcheck.sh'
        - '/autoins'
        - '/BarracudaMailService'
        - '/etc/cron.daily/core_check.sh'
        - '/etc/cron.daily/core.sh'
        - '/etc/cron.hourly/aacore.sh'
        - '/etc/cron.hourly/appcheck.sh'
        - '/etc/cron.hourly/core.sh'
        - '/get_fs_info.pl'
        - '/imgdata.jpg'
        - '/install_att_v2.tar'
        - '/install_bvp74_auth.tar'
        - '/install_helo.tar'
        - '/install_reuse.tar'
        - '/intent_helo'
        - '/intent_reuse'
        - '/intentbas'
        # - '/mknod'
        - '/mod_attachment.lua'
        - '/mod_content.lua'
        - '/mod_require_helo.lua'
        - '/mod_rtf'
        - '/mod_sender.lua'
        - '/mod_udp.so'
        - '/nfsd_stub.ko'
        - '/resize_reisertab'
        - '/resize_risertab'
        - '/resize2fstab'
        - '/rverify'
        - '/saslautchd'
        - '/sendscd'
        - '/snapshot.tar'
        - '/tmp/p'
        - '/tmp/p7'
        - '/tmp/t'
        - '/update_v2.sh'
        - '/update_v31.sh'
        - '/update_v35.sh'
        - '/update_version'
condition: selection

False positives (as the rule lists them)

  • Unlikely

Tags

  • attack.execution
  • attack.persistence
  • detection.emerging-threats
  • attack.stealth

References

Read on 2026-11-03T00:58:21.399Z under licence sigma-drl-1.1@d5f4c36a from https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules-emerging-threats/2023/TA/UNC4841-Barracuda-ESG-Zero-Day-Exploitation/file_event_lnx_apt_unc4841_file_indicators.yml

Sources and licences

  • SigmaHQ

    "UNC4841 - Barracuda ESG Exploitation Indicators" by Nasreddine Bencherchali (Nextron Systems) (SigmaHQ). Rule: https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules-emerging-threats/2023/TA/UNC4841-Barracuda-ESG-Zero-Day-Exploitation/file_event_lnx_apt_unc4841_file_indicators.yml.
    Licensed under the Detection Rule License (DRL) 1.1: https://github.com/SigmaHQ/Detection-Rule-License

    Detection Rule License (DRL) 1.1

Cite this page

Dragons Eye Ransomware Tracker, "Sigma rule: UNC4841 - Barracuda ESG Exploitation Indicators",
entity page, dataset version ref-9eed07b12cb9, updated 2025-08-19T00:00:00.000Z,
https://ransomware-tracker.com/detections/sigma/5627c337-a9b2-407a-a82d-5fd97035ff39 (accessed 2026-11-03).
Underlying source: SigmaHQ rule 5627c337-a9b2-407a-a82d-5fd97035ff39, commit ccbb0369507f796db0b0ae6854c8a2be471b9d84.

Pages change. The dataset version identifies the data, but no archive of old versions is kept, so this citation cannot be replayed later.