Sigma rule: IcedID Malware Suspicious Single Digit DLL Execution Via Rundll32

Rule

Title

IcedID Malware Suspicious Single Digit DLL Execution Via Rundll32

Status

test

Level

high

Author

Nasreddine Bencherchali (Nextron Systems)

Date

2023-08-31

File

rules-emerging-threats/2023/Malware/IcedID/proc_creation_win_malware_icedid_rundll32_dllregisterserver.yml

Commit

ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects RunDLL32.exe executing a single digit DLL named "1.dll" with the export function "DllRegisterServer". This behaviour was often seen used by malware and especially IcedID

Log source

product

windows

category

process_creation

Detection

selection:
    Image|endswith: '\rundll32.exe'
    CommandLine|endswith:
        - '\1.dll, DllRegisterServer' # In case of full path exec
        - ' 1.dll, DllRegisterServer' # In case of direct exec
condition: selection

False positives (as the rule lists them)

• Unknown

Tags

• attack.stealth
• attack.t1218.011
• detection.emerging-threats

MITRE ATT&CK ids this rule names

• T1218.011

References

• https://thedfirreport.com/2023/05/22/icedid-macro-ends-in-nokoyawa-ransomware/
• https://thedfirreport.com/2023/08/28/html-smuggling-leads-to-domain-wide-ransomware/

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/IcedID/proc_creation_win_malware_icedid_rundll32_dllregisterserver.yml