{"id":"e62a9f0c-ca1e-46b2-85d5-a6da77f86d1a","title":"File Encoded To Base64 Via Certutil.EXE","description":"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","author":"Florian Roth (Nextron Systems), Jonhnathan Ribeiro, oscd.community, Nasreddine Bencherchali (Nextron Systems)","status":"test","level":"medium","date":"2019-02-24","modified":"2024-03-05","tags":["attack.stealth","attack.t1027"],"technique_ids":["T1027"],"logsource":{"category":"process_creation","product":"windows"},"falsepositives":["As this is a general purpose rule, legitimate usage of the encode functionality will trigger some false positives. Apply additional filters accordingly"],"references":["https://learn.microsoft.com/en-us/windows-server/administration/windows-commands/certutil","https://unit42.paloaltonetworks.com/new-babyshark-malware-targets-u-s-national-security-think-tanks/","https://lolbas-project.github.io/lolbas/Binaries/Certutil/"],"source_path":"rules/windows/process_creation/proc_creation_win_certutil_encode.yml","source_sha256":"7772ab83ef885b07904dbcc7824ce86d2a907fa9eec9c95861251cae02ab9e76","source_url":"https://github.com/anpa1200/sigma/blob/b249e9683190cffdcaf188ccbfb90bf4759844e1/rules/windows/process_creation/proc_creation_win_certutil_encode.yml","license":"Detection Rule License 1.1","license_url":"https://github.com/SigmaHQ/Detection-Rule-License/blob/main/LICENSE.Detection.Rules.md","yaml":"title: File Encoded To Base64 Via Certutil.EXE\nid: e62a9f0c-ca1e-46b2-85d5-a6da77f86d1a\nstatus: test\ndescription: 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\nreferences:\n    - https://learn.microsoft.com/en-us/windows-server/administration/windows-commands/certutil\n    - https://unit42.paloaltonetworks.com/new-babyshark-malware-targets-u-s-national-security-think-tanks/\n    - https://lolbas-project.github.io/lolbas/Binaries/Certutil/\nauthor: Florian Roth (Nextron Systems), Jonhnathan Ribeiro, oscd.community, Nasreddine Bencherchali (Nextron Systems)\ndate: 2019-02-24\nmodified: 2024-03-05\ntags:\n    - attack.stealth\n    - attack.t1027\nlogsource:\n    category: process_creation\n    product: windows\ndetection:\n    selection_img:\n        - Image|endswith: '\\certutil.exe'\n        - OriginalFileName: 'CertUtil.exe'\n    selection_cli:\n        CommandLine|contains|windash: '-encode'\n    condition: all of selection_*\nfalsepositives:\n    - As this is a general purpose rule, legitimate usage of the encode functionality will trigger some false positives. Apply additional filters accordingly\nlevel: medium\nregression_tests_path: regression_data/rules/windows/process_creation/proc_creation_win_certutil_encode/info.yml\n","validation":"yaml_parsed_not_backend_compiled_or_live_validated","techniques":[{"key":"enterprise/T1027","id":"T1027","name":"Obfuscated Files or Information","page":"techniques/enterprise/T1027/"}],"data_path":"data/detection-rules/e62a9f0c-ca1e-46b2-85d5-a6da77f86d1a.json","kind":"sigma"}