Rundll32 UNC Path Execution

 1title: Rundll32 UNC Path Execution
 2id: 5cdb711b-5740-4fb2-ba88-f7945027afac
 3status: test
 4description: |
 5    Detects rundll32 execution where the DLL is located on a remote location (share).
 6    Threat actors can abuse the rundll32.exe binary to execute remote DLLs from a UNC pathh.    
 7references:
 8    - https://www.cybereason.com/blog/rundll32-the-infamous-proxy-for-executing-malicious-code
 9    - https://www.microsoft.com/en-us/security/blog/2026/07/16/acr-stealer-two-observed-intrusion-chains-amid-increased-threat-activity/
10author: Nasreddine Bencherchali (Nextron Systems)
11date: 2022-08-10
12modified: 2026-07-20
13tags:
14    - attack.execution
15    - attack.lateral-movement
16    - attack.stealth
17    - attack.t1021.002
18    - attack.t1218.011
19logsource:
20    category: process_creation
21    product: windows
22detection:
23    selection_img:
24        - Image|endswith: '\rundll32.exe'
25        - OriginalFileName: 'RUNDLL32.EXE'
26        - CommandLine|contains: 'rundll32'
27    selection_cli:
28        CommandLine|contains:
29            - ' \\\\'
30            - ' ''\\\\'
31            - ' "\\\\'
32    filter_main_cli_pipe:
33        CommandLine|contains: '\\\\.\\pipe'
34    condition: all of selection_* and not 1 of filter_main_*
35falsepositives:
36    - Unlikely
37level: high
38regression_tests_path: regression_data/rules/windows/process_creation/proc_creation_win_rundll32_unc_path/info.yml