Detection rules › Sigma
Suspicious Double Extension Files
Detects dropped files with double extensions, which is often used by malware as a method to abuse the fact that Windows hide default extensions by default.
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Defense Evasion | T1036.007 Masquerading: Double File Extension |
Event coverage
| Provider | Event ID | Title |
|---|---|---|
| Sysmon | 11 | FileCreate |
Stages and Predicates
Stage 1: 1 of selection_gen
or:
TargetFilename|endswith: .exe
TargetFilename|endswith: .iso
TargetFilename|endswith: .rar
TargetFilename|endswith: .svg
TargetFilename|endswith: .zip
or:
TargetFilename|contains: .doc.
TargetFilename|contains: .docx.
TargetFilename|contains: .gif.
TargetFilename|contains: .jpeg.
TargetFilename|contains: .jpg.
TargetFilename|contains: .mp3.
TargetFilename|contains: .mp4.
TargetFilename|contains: .pdf.
TargetFilename|contains: .png.
TargetFilename|contains: .ppt.
TargetFilename|contains: .pptx.
TargetFilename|contains: .rtf.
TargetFilename|contains: .svg.
TargetFilename|contains: .txt.
TargetFilename|contains: .xls.
TargetFilename|contains: .xlsx.
Stage 2: 1 of selection_exe
or:
TargetFilename|endswith: .rar.exe
TargetFilename|endswith: .zip.exe
Stage 3: not 1 of filter_icons_linux
TargetFilename|startswith: '/usr/share/icons/'
Indicators
Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.
| Field | Kind | Values |
|---|---|---|
TargetFilename | ends_with |
|
TargetFilename | match |
|
TargetFilename | starts_with |
|