Detection rules › Sigma
Suspicious File Encoded To Base64 Via Certutil.EXE
Detects the execution of certutil with the "encode" flag to encode a file to base64 where the extensions of the file is suspicious
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Defense Evasion | T1027 Obfuscated Files or Information |
Event coverage
| Provider | Event ID | Title |
|---|---|---|
| Sysmon | 1 | Process creation |
Stages and Predicates
Stage 1: all of selection_img
or:
Image|endswith: '\certutil.exe'
OriginalFileName: CertUtil.exe
Stage 2: all of selection_cli
CommandLine|contains: -encode
Stage 3: all of selection_extension
or:
CommandLine|contains: .acl
CommandLine|contains: .bat
CommandLine|contains: .doc
CommandLine|contains: .gif
CommandLine|contains: .jpeg
CommandLine|contains: .jpg
CommandLine|contains: .mp3
CommandLine|contains: .pdf
CommandLine|contains: .png
CommandLine|contains: .ppt
CommandLine|contains: .tmp
CommandLine|contains: .xls
CommandLine|contains: .xml
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 |
|---|---|---|
CommandLine | match |
|
Image | ends_with |
|
OriginalFileName | eq |
|