Legitimate Application Dropped Script

 1title: Legitimate Application Dropped Script
 2id: 7d604714-e071-49ff-8726-edeb95a70679
 3status: test
 4description: |
 5    Detects LOLBINs and applications that should not legitimately drop script files to disk.
 6    This may indicate malware staging or abuse of a trusted binary for script-based code execution.    
 7references:
 8    - https://github.com/Neo23x0/sysmon-config/blob/3f808d9c022c507aae21a9346afba4a59dd533b9/sysmonconfig-export-block.xml#L1326
 9    - https://dmpdump.github.io/posts/TelegramRat/
10    - https://www.virustotal.com/gui/file/a0d5b30578acd1df9139e7a8a4bfc659dc2cf48f4dc0c5804b70890adeb9fa21/behavior
11author: frack113, Florian Roth (Nextron Systems)
12date: 2022-08-21
13modified: 2026-05-11
14tags:
15    - attack.stealth
16    - attack.t1218
17logsource:
18    product: windows
19    category: file_event
20detection:
21    selection:
22        Image|endswith:
23            # Microsoft Office Programs Dropping Executables / Rest of the apps are covered in: c7a74c80-ba5a-486e-9974-ab9e682bc5e4
24            - \eqnedt32.exe
25            - \wordpad.exe
26            - \wordview.exe
27            # LOLBINs that can be used to download executables
28            - \certutil.exe
29            - \certoc.exe
30            - \CertReq.exe
31            # - \bitsadmin.exe (depends on the environment; comment in if you're sure that bitsadmin doesn't do that in your env)
32            - \Desktopimgdownldr.exe
33            - \esentutl.exe
34            # - \expand.exe
35            - '\mshta.exe'
36            # Executables that should never drop an executable to disk (but may after a previous process injection or if it's malware that uses a legitimate name)
37            - '\AcroRd32.exe'
38            - '\RdrCEF.exe'
39            - '\hh.exe'
40            - '\finger.exe'
41        TargetFilename|endswith:
42            - '.bat'
43            - '.chm'
44            - '.csproj'
45            - '.hta'
46            - '.js'
47            - '.jse'
48            - '.proj'
49            - '.ps1'
50            - '.py'
51            - '.scf'
52            - '.vbe'
53            - '.vbs'
54            - '.wsf'
55            - '.wsh'
56    filter_main_mshta:
57        Image|endswith: '\mshta.exe'
58        TargetFilename|endswith: '.hta'
59    condition: selection and not 1 of filter_main_*
60falsepositives:
61    - Unknown
62level: high
63regression_tests_path: regression_data/rules/windows/file/file_event/file_event_win_susp_legitimate_app_dropping_script/info.yml