Linux grep file discovery targeting GobRAT-specific filenames

Alerts on grep executions on Linux whose arguments contain specific malware-related file names for discovery.

FreeReviewedSigma · High · v2

Product: linux
Category: process_creation
Author: Joseliyo Sanchez, @Joseliyo_Jstnk (SigmaHQ), DRL 1.1
Published: 2023-06-02
Updated: 2026-07-31

ATT&CK techniques

Discovery

Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
- T1082System Information Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule identifies Linux process executions of /grep where the command line contains filenames associated with potential GobRAT activity (apached, frpc, sshd.sh, zone.arm). Attackers often use grep to quickly enumerate or confirm the presence of specific files during staging and discovery. The detection relies on process creation telemetry, specifically the executed image path ending in /grep and matching substrings within the command line.

Reporting behind it

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Linux grep file discovery targeting GobRAT-specific filenames

Pivot detection · T1082 · 9 related

Changelog

v2
Candidate ingested via manual entry.2026-07-31
v1
No changelog recorded for this version.2026-07-30

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.

linux-grep-command-used-to-locate-specific-malware-related-files-process-discove-e34cfa0c

title: Linux grep file discovery targeting GobRAT-specific filenames
id: 57842cca-b388-4e69-9b43-76fb4584a429
status: test
description: This rule identifies Linux process executions of /grep where the command line contains filenames associated with potential GobRAT activity (apached, frpc, sshd.sh, zone.arm). Attackers often use grep to quickly enumerate or confirm the presence of specific files during staging and discovery. The detection relies on process creation telemetry, specifically the executed image path ending in /grep and matching substrings within the command line.
references:
  - https://blogs.jpcert.or.jp/en/2023/05/gobrat.html
  - https://www.virustotal.com/gui/file/60bcd645450e4c846238cf0e7226dc40c84c96eba99f6b2cffcd0ab4a391c8b3/detection
  - https://www.virustotal.com/gui/file/3e44c807a25a56f4068b5b8186eee5002eed6f26d665a8b791c472ad154585d1/detection
  - https://github.com/SigmaHQ/sigma/blob/master/rules/linux/process_creation/proc_creation_lnx_malware_gobrat_grep_payload_discovery.yml
author: Joseliyo Sanchez, @Joseliyo_Jstnk, Huntrule Team
date: 2023-06-02
tags:
  - attack.discovery
  - attack.t1082
logsource:
  category: process_creation
  product: linux
detection:
  selection:
    Image|endswith: /grep
    CommandLine|contains:
      - apached
      - frpc
      - sshd.sh
      - zone.arm
  condition: selection
falsepositives:
  - Unknown
level: high
license: DRL-1.1
related:
  - id: e34cfa0c-0a50-4210-9cb3-5632d08eb041
    type: derived

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