Sigma rule: Injected Browser Process Spawning Rundll32 - GuLoader Activity

Rule

Title

Injected Browser Process Spawning Rundll32 - GuLoader Activity

Status

test

Level

high

Author

@kostastsale

Date

2023-08-07

File

rules-emerging-threats/2023/Malware/GuLoader/proc_creation_win_malware_guloader_execution.yml

Commit

ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects the execution of installed GuLoader malware on the host.
GuLoader is initiating network connections via the rundll32.exe process that is spawned via a browser parent(injected) process.

Log source

product

windows

category

process_creation

Detection

selection:
    ParentImage|endswith:
        - '\chrome.exe'
        - '\firefox.exe'
        - '\msedge.exe'
    Image|endswith: '\rundll32.exe'
    CommandLine|endswith: '\rundll32.exe'
condition: selection

False positives (as the rule lists them)

• Unlikely

Tags

• attack.privilege-escalation
• attack.stealth
• attack.t1055
• detection.emerging-threats

MITRE ATT&CK ids this rule names

• T1055

References

• Internal Research

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/Malware/GuLoader/proc_creation_win_malware_guloader_execution.yml