Suspicious FileFix Execution Pattern
Detects suspicious FileFix execution patterns where users are tricked into running malicious commands through browser file upload dialog manipulation. This attack typically begins when users visit malicious websites impersonating legitimate services or news platforms, which may display fake CAPTCHA challenges or direct instructions to open file explorer and paste clipboard content. The clipboard content usually contains commands that download and execute malware, such as information stealing tools.
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Events generated when a new process is spawned on the system. Covers command-line arguments, parent/child relationships, and process metadata.
detection:
selection_exec_parent:
# This is case where phishing pages trick users to paste commands in browser file upload dialog
ParentImage|endswith:
- '\brave.exe'
- '\chrome.exe'
- '\firefox.exe'
- '\msedge.exe'
CommandLine|contains: '#'
selection_cli_lolbin:
CommandLine|contains:
- '%comspec%'
- 'bitsadmin'
- 'certutil'
- 'cmd'
- 'cscript'
- 'curl'
- 'finger'
- 'mshta'
- 'powershell'
- 'pwsh'
- 'regsvr32'
- 'rundll32'
- 'schtasks'
- 'wget'
- 'wscript'
selection_cli_captcha:
CommandLine|contains:
- 'account'
- 'anti-bot'
- 'botcheck'
- 'captcha'
- 'challenge'
- 'confirmation'
- 'fraud'
- 'human'
- 'identification'
- 'identificator'
- 'identity'
- 'robot'
- 'validation'
- 'verification'
- 'verify'
condition: selection_exec_parent and 1 of selection_cli_*Legitimate use of PowerShell or other utilities launched from browser extensions or automation tools
Tactics
Other
FileFix - Command Evidence in TypedPaths
Detects commonly-used chained commands and strings in the most recent 'url' value of the 'TypedPaths' key, which could be indicative of a user being targeted by the FileFix technique.
Detects similar activity. Both rules may fire on overlapping events.
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