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Detectionmediumtest

Suspicious Access to Sensitive File Extensions

Detects known sensitive file extensions accessed on a network share

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Samir BousseadenCreated Wed Apr 03Updated Fri Oct 1791c945bc-2ad1-4799-a591-4d00198a1215windows
Log Source
Windowssecurity
ProductWindows← raw: windows
Servicesecurity← raw: security
Detection Logic
Detection Logic1 selector
detection:
    selection:
        EventID: 5145
        RelativeTargetName|endswith:
            - '.bak'
            - '.dmp'
            - '.edb'
            - '.kirbi'
            - '.msg'
            - '.nsf'
            - '.nst'
            - '.oab'
            - '.ost'
            - '.pst'
            - '.rdp'
            # - '\groups.xml'  # Commented out: groups.xml is accessed legitimately by Group Policy processing; high FP rate in enterprise environments
    condition: selection
False Positives

Help Desk operator doing backup or re-imaging end user machine or backup software

Users working with these data types or exchanging message files

References
1
Resolving title…
Internal Research
MITRE ATT&CK
Related Rules
SimilarDetectionmedium

Suspicious Access to Sensitive File Extensions - Zeek

Detects known sensitive file extensions via Zeek

Detects similar activity. Both rules may fire on overlapping events.

Rule Metadata
Rule ID
91c945bc-2ad1-4799-a591-4d00198a1215
Status
test
Level
medium
Type
Detection
Created
Wed Apr 03
Modified
Fri Oct 17
Author
Samir Bousseaden
Path
rules/windows/builtin/security/win_security_susp_raccess_sensitive_fext.yml
Raw Tags
attack.collectionattack.t1039
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