UNC4841 - Barracuda ESG Exploitation Indicators

title: UNC4841 - Barracuda ESG Exploitation Indicators
id: 5627c337-a9b2-407a-a82d-5fd97035ff39
status: test
description: Detects file indicators as seen used by UNC4841 during their Barracuda ESG zero day exploitation.
references:
    - https://www.mandiant.com/resources/blog/barracuda-esg-exploited-globally
author: Nasreddine Bencherchali (Nextron Systems)
date: 2023-06-16
modified: 2025-08-19
tags:
    - attack.execution
    - attack.persistence
    - detection.emerging-threats
    - attack.stealth
logsource:
    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
falsepositives:
    - Unlikely
level: high