Detectionhighexperimental

Suspicious File Created in Outlook Temporary Directory

Detects the creation of files with suspicious file extensions in the temporary directory that Outlook uses when opening attachments. This can be used to detect spear-phishing campaigns that use suspicious files as attachments, which may contain malicious code.

Convert In Phoenix Studio

Open this Sigma rule in the converter with the YAML preloaded and ready for backend selection.

Launch

Florian Roth (Nextron Systems), Swachchhanda Shrawan Poudel (Nextron Systems)Created Tue Jul 22fabb0e80-030c-4e3e-a104-d09676991ac3windows

Log Source

WindowsFile Event

ProductWindows← raw: windows

CategoryFile Event← raw: file_event

Events for file system activity including creation, modification, and deletion.

Detection Logic

detection:
    selection_extension:
        TargetFilename|endswith:
            - '.cpl'
            - '.hta'
            - '.iso'
            - '.rdp'
            - '.svg'
            - '.vba'
            - '.vbe'
            - '.vbs'
    selection_location:
        - TargetFilename|contains:
              - '\AppData\Local\Packages\Microsoft.Outlook_'
              - '\AppData\Local\Microsoft\Olk\Attachments\'
        - TargetFilename|contains|all:
              - '\AppData\Local\Microsoft\Windows\'
              - '\Content.Outlook\'
    condition: all of selection_*