IcedID Malware Suspicious Single Digit DLL Execution Via Rundll32

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

Sigma rule (View on GitHub)

 1title: IcedID Malware Suspicious Single Digit DLL Execution Via Rundll32
 2id: 2bd8e100-5b3b-4b6a-bbb5-b129d3ddddc5
 3status: test
 4description: 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
 5references:
 6    - https://thedfirreport.com/2023/05/22/icedid-macro-ends-in-nokoyawa-ransomware/
 7    - https://thedfirreport.com/2023/08/28/html-smuggling-leads-to-domain-wide-ransomware/
 8author: Nasreddine Bencherchali (Nextron Systems)
 9date: 2023-08-31
10tags:
11    - attack.defense-evasion
12    - attack.t1218.011
13    - detection.emerging-threats
14logsource:
15    category: process_creation
16    product: windows
17detection:
18    selection:
19        Image|endswith: '\rundll32.exe'
20        CommandLine|endswith:
21            - '\1.dll, DllRegisterServer' # In case of full path exec
22            - ' 1.dll, DllRegisterServer' # In case of direct exec
23    condition: selection
24falsepositives:
25    - Unknown
26level: high

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