Sigma rule: Legitimate Application Writing Files In Uncommon Location

Rule

Title

Legitimate Application Writing Files In Uncommon Location

Status

experimental

Level

high

Author

Swachchhanda Shrawan Poudel (Nextron Systems)

Date

2025-12-10

Modified

2026-10-14

File

rules/windows/file/file_event/file_event_win_susp_legitimate_app_dropping_in_uncommon_location.yml

Commit

ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects legitimate applications writing any type of file to uncommon or suspicious locations that are not typical for application data storage or execution.
Adversaries may leverage legitimate applications (Living off the Land Binaries - LOLBins) to drop or download malicious files to uncommon locations on the system to evade detection by security solutions.

Log source

product

windows

category

file_event

Detection

selection_img:
    Image|endswith:
        # Microsoft Office Programs Dropping Executables / Rest of the apps are covered in: c7a74c80-ba5a-486e-9974-ab9e682bc5e4
        - '\eqnedt32.exe'
        - '\wordpad.exe'
        - '\wordview.exe'
        # LOLBINs that can be used to download executables
        - '\cmdl32.exe'
        - '\certutil.exe'
        - '\certoc.exe'
        - '\CertReq.exe'
        - '\bitsadmin.exe'
        - '\Desktopimgdownldr.exe'
        - '\esentutl.exe'
        - '\expand.exe'
        - '\extrac32.exe'
        - '\replace.exe'
        - '\mshta.exe'
        - '\ftp.exe'
        - '\Ldifde.exe'
        - '\RdrCEF.exe'
        - '\hh.exe'
        - '\finger.exe'
        - '\findstr.exe'
selection_locations:
    TargetFilename|contains:
        - ':\Perflogs'
        - ':\ProgramData\'
        - ':\Temp\'
        - ':\Users\Public\'
        - ':\Windows\'
        - '\$Recycle.Bin\'
        - '\AppData\Local\'
        - '\AppData\Roaming\'
        - '\Contacts\'
        - '\Desktop\'
        - '\Favorites\'
        - '\Favourites\'
        - '\inetpub\wwwroot\'
        - '\Music\'
        - '\Pictures\'
        - '\Start Menu\Programs\Startup\'
        - '\Users\Default\'
        - '\Videos\'
filter_optional_dell_techhub_repair:
    # Dell TechHub runs "esentutl /p" on its SRUDB copy; the repair scratch files land in the working directory (System32)
    Image|endswith: '\esentutl.exe'
    TargetFilename|startswith:
        - 'C:\Windows\System32\SRUDB_'
        - 'C:\Windows\System32\TEMPREPAIR'
    TargetFilename|endswith:
        - '.INTEG.RAW'
        - '.EDB'
filter_optional_dell_techhub_copy:
    Image|endswith: '\esentutl.exe'
    TargetFilename|startswith: 'C:\ProgramData\Dell\DTP\DB\SRUDBData\'
condition: all of selection_* and not 1 of filter_optional_*

False positives (as the rule lists them)

• Unknown

Tags

• attack.stealth
• attack.t1218
• attack.command-and-control
• attack.t1105

MITRE ATT&CK ids this rule names

• T1105
• T1218

Related rules

• 2ddef153-167b-4e89-86b6-757a9e65dcac (similar)

References

• https://lolbas-project.github.io/#/download

Read on 2026-11-03T00:58:21.399Z under licence sigma-drl-1.1@d5f4c36a from https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/file/file_event/file_event_win_susp_legitimate_app_dropping_in_uncommon_location.yml