Sigma rule: UNC4841 - Email Exfiltration File Pattern

A detection rule from the SigmaHQ repository, shown as its author published it. Dataset version ref-2324b3fb8673, updated 2023-06-16T00:00:00.000Z.

Rule

Title
UNC4841 - Email Exfiltration File Pattern
Status
test
Level
high
Author
Nasreddine Bencherchali (Nextron Systems)
Date
2023-06-16
File
rules-emerging-threats/2023/TA/UNC4841-Barracuda-ESG-Zero-Day-Exploitation/file_event_lnx_apt_unc4841_exfil_mail_pattern.yml
Commit
ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects filename pattern of email related data used by UNC4841 for staging and exfiltration

Log source

product
linux
category
file_event

Detection

selection:
    TargetFilename|re: '/mail/tmp/[a-zA-Z0-9]{3}[0-9]{3}\.tar\.gz'
condition: selection

False positives (as the rule lists them)

  • Unknown

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_exfil_mail_pattern.yml

Sources and licences

  • SigmaHQ

    "UNC4841 - Email Exfiltration File Pattern" 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_exfil_mail_pattern.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 - Email Exfiltration File Pattern",
entity page, dataset version ref-2324b3fb8673, updated 2023-06-16T00:00:00.000Z,
https://ransomware-tracker.com/detections/sigma/0785f462-60b0-4031-9ff4-b4f3a0ba589a (accessed 2026-11-03).
Underlying source: SigmaHQ rule 0785f462-60b0-4031-9ff4-b4f3a0ba589a, 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.