{"id":"d75d6b6b-adb9-48f7-824b-ac2e786efe1f","title":"Suspicious FromBase64String Usage On Gzip Archive - Process Creation","description":"Detects attempts of decoding a base64 Gzip archive via PowerShell. This technique is often used as a method to load malicious content into memory afterward.","author":"frack113","status":"test","level":"medium","date":"2022-12-23","modified":"","tags":["attack.command-and-control","attack.t1132.001"],"technique_ids":["T1132.001"],"logsource":{"product":"windows","category":"process_creation"},"falsepositives":["Legitimate administrative script"],"references":["https://speakerdeck.com/heirhabarov/hunting-for-powershell-abuse?slide=43"],"source_path":"rules/windows/process_creation/proc_creation_win_powershell_frombase64string_archive.yml","source_sha256":"9a09d9e99a77b2a18321f6dcc3eb8d1c950d96f59d0ea41016523fafc3ef9c41","source_url":"https://github.com/anpa1200/sigma/blob/b249e9683190cffdcaf188ccbfb90bf4759844e1/rules/windows/process_creation/proc_creation_win_powershell_frombase64string_archive.yml","license":"Detection Rule License 1.1","license_url":"https://github.com/SigmaHQ/Detection-Rule-License/blob/main/LICENSE.Detection.Rules.md","yaml":"title: Suspicious FromBase64String Usage On Gzip Archive - Process Creation\nid: d75d6b6b-adb9-48f7-824b-ac2e786efe1f\nrelated:\n    - id: df69cb1d-b891-4cd9-90c7-d617d90100ce\n      type: similar\nstatus: test\ndescription: Detects attempts of decoding a base64 Gzip archive via PowerShell. This technique is often used as a method to load malicious content into memory afterward.\nreferences:\n    - https://speakerdeck.com/heirhabarov/hunting-for-powershell-abuse?slide=43\nauthor: frack113\ndate: 2022-12-23\ntags:\n    - attack.command-and-control\n    - attack.t1132.001\nlogsource:\n    product: windows\n    category: process_creation\ndetection:\n    selection:\n        CommandLine|contains|all:\n            - 'FromBase64String'\n            - 'MemoryStream'\n            - 'H4sI'\n    condition: selection\nfalsepositives:\n    - Legitimate administrative script\nlevel: medium\n","validation":"yaml_parsed_not_backend_compiled_or_live_validated","techniques":[{"key":"enterprise/T1132.001","id":"T1132.001","name":"Standard Encoding","page":"techniques/enterprise/T1132.001/"}],"data_path":"data/detection-rules/d75d6b6b-adb9-48f7-824b-ac2e786efe1f.json","kind":"sigma"}