{"id":"30edb182-aa75-42c0-b0a9-e998bb29067c","title":"Potential AMSI Bypass Via .NET Reflection","description":"Detects Request to \"amsiInitFailed\" that can be used to disable AMSI Scanning","author":"Markus Neis, @Kostastsale","status":"test","level":"high","date":"2018-08-17","modified":"2023-02-03","tags":["attack.defense-impairment","attack.t1685"],"technique_ids":["T1685"],"logsource":{"category":"process_creation","product":"windows"},"falsepositives":["Unlikely"],"references":["https://s3cur3th1ssh1t.github.io/Bypass_AMSI_by_manual_modification/","https://www.mdsec.co.uk/2018/06/exploring-powershell-amsi-and-logging-evasion/"],"source_path":"rules/windows/process_creation/proc_creation_win_powershell_amsi_init_failed_bypass.yml","source_sha256":"454a6ee07a70cf8c74e333f89a2acaf62c8c9fbff6783e8429303778114457f1","source_url":"https://github.com/anpa1200/sigma/blob/b249e9683190cffdcaf188ccbfb90bf4759844e1/rules/windows/process_creation/proc_creation_win_powershell_amsi_init_failed_bypass.yml","license":"Detection Rule License 1.1","license_url":"https://github.com/SigmaHQ/Detection-Rule-License/blob/main/LICENSE.Detection.Rules.md","yaml":"title: Potential AMSI Bypass Via .NET Reflection\nid: 30edb182-aa75-42c0-b0a9-e998bb29067c\nrelated:\n    - id: 4f927692-68b5-4267-871b-073c45f4f6fe\n      type: obsolete\nstatus: test\ndescription: Detects Request to \"amsiInitFailed\" that can be used to disable AMSI Scanning\nreferences:\n    - https://s3cur3th1ssh1t.github.io/Bypass_AMSI_by_manual_modification/\n    - https://www.mdsec.co.uk/2018/06/exploring-powershell-amsi-and-logging-evasion/\nauthor: Markus Neis, @Kostastsale\ndate: 2018-08-17\nmodified: 2023-02-03\ntags:\n    - attack.defense-impairment\n    - attack.t1685\nlogsource:\n    category: process_creation\n    product: windows\ndetection:\n    selection:\n        - CommandLine|contains|all:\n              - 'System.Management.Automation.AmsiUtils'\n              - 'amsiInitFailed'\n        - CommandLine|contains|all:\n              - '[Ref].Assembly.GetType'\n              - 'SetValue($null,$true)'\n              - 'NonPublic,Static'\n    condition: selection\nfalsepositives:\n    - Unlikely\nlevel: high\n","validation":"yaml_parsed_not_backend_compiled_or_live_validated","techniques":[{"key":"enterprise/T1685","id":"T1685","name":"Disable or Modify Tools","page":"techniques/enterprise/T1685/"}],"data_path":"data/detection-rules/30edb182-aa75-42c0-b0a9-e998bb29067c.json","kind":"sigma"}