Detection rules › Kusto Query Language
NRT Process executed from binary hidden in Base64 encoded file
'Encoding malicious software is a technique used to obfuscate files from detection. The first CommandLine component is looking for Python decoding base64. The second CommandLine component is looking for Bash/sh command line base64 decoding. The third one is looking for Ruby decoding base64.'
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Execution | T1059 Command and Scripting Interpreter |
| Defense Evasion | T1027 Obfuscated Files or Information, T1140 Deobfuscate/Decode Files or Information |
Event coverage
| Provider | Event ID | Title |
|---|---|---|
| Security-Auditing | 4688 | A new process has been created. |
Stages and Predicates
Stage 1: source
SecurityEvent
Stage 2: where
EventID eq "4688"
Stage 3: where
CommandLine is_not_null
Stage 4: project
Stage 5: extend
Stage 6: extend
Stage 7: where
or
CommandLine contains ".decode('base64')"
CommandLine contains ".decode64("
CommandLine contains "base64 --decode"
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 | contains |
|
EventID | eq |
|