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Detection rules › Sigma

UNC4841 - Email Exfiltration File Pattern

Status
test
Severity
high
Log source
product linux, category file_event
Author
Nasreddine Bencherchali (Nextron Systems)
Source
github.com/SigmaHQ/sigma

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

MITRE ATT&CK coverage

TacticTechniques
ExecutionNo specific technique
PersistenceNo specific technique
StealthNo specific technique

Event coverage

ProviderEvent
Sysmon-for-LinuxEvent ID 11

Rule body yaml

title: UNC4841 - Email Exfiltration File Pattern
id: 0785f462-60b0-4031-9ff4-b4f3a0ba589a
status: test
description: Detects filename pattern of email related data used by UNC4841 for staging and exfiltration
references:
    - https://www.mandiant.com/resources/blog/barracuda-esg-exploited-globally
author: Nasreddine Bencherchali (Nextron Systems)
date: 2023-06-16
tags:
    - attack.execution
    - attack.persistence
    - detection.emerging-threats
    - attack.stealth
logsource:
    product: linux
    category: file_event
detection:
    selection:
        TargetFilename|re: '/mail/tmp/[a-zA-Z0-9]{3}[0-9]{3}\.tar\.gz'
    condition: selection
falsepositives:
    - Unknown
level: high

Stages and Predicates

Stage 0: condition

selection

Stage 1: selection

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

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

FieldKindValues
TargetFilenameregex_match
  • /mail/tmp/[a-zA-Z0-9]{3}[0-9]{3}.tar.gz