Detectionmediumtest
File Encoded To Base64 Via Certutil.EXE
Detects the execution of certutil with the "encode" flag to encode a file to base64. This can be abused by threat actors and attackers for data exfiltration
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Launch
Florian Roth (Nextron Systems), Jonhnathan Ribeiro, oscd.community, Nasreddine Bencherchali (Nextron Systems)Created Sun Feb 24Updated Tue Mar 05e62a9f0c-ca1e-46b2-85d5-a6da77f86d1awindows
Log Source
WindowsProcess Creation
ProductWindows← raw: windows
CategoryProcess Creation← raw: process_creation
Events generated when a new process is spawned on the system. Covers command-line arguments, parent/child relationships, and process metadata.
Detection Logic
Detection Logic2 selectors
detection:
selection_img:
- Image|endswith: '\certutil.exe'
- OriginalFileName: 'CertUtil.exe'
selection_cli:
CommandLine|contains|windash: '-encode'
condition: all of selection_*False Positives
As this is a general purpose rule, legitimate usage of the encode functionality will trigger some false positives. Apply additional filters accordingly
References
MITRE ATT&CK
Tactics
Techniques
Rule Metadata
Rule ID
e62a9f0c-ca1e-46b2-85d5-a6da77f86d1a
Status
test
Level
medium
Type
Detection
Created
Sun Feb 24
Modified
Tue Mar 05
Author
Path
rules/windows/process_creation/proc_creation_win_certutil_encode.yml
Raw Tags
attack.defense-evasionattack.t1027