Windows Defender - Quarantine

Overview

Windows Defender quarantines files that were detected as malicious, storing and encrypting (in RC4) the full content of the files. The quarantined files can be restored, or deleted permanently, by the end user. It is thus possible to recover the files put in quarantine by Windows Defender for further investigations.

Additionally, Windows Defender stores some metadata on every detection under the Windows Defender\Quarantine folder. The information is similarly stored in RC4-encrypted files.

Information of interest

The quarantined files are stored under: %SystemDrive%\ProgramData\Microsoft\Windows Defender\Quarantine\ResourceData. The RC4 key used to encrypt the file is hardcoded (in the mpengine.dll DLL).

The metadata of every detections are stored under: %SystemDrive%\ProgramData\Microsoft\Windows Defender\Quarantine\Entries.

For each quarantined file, its associated metadata notably includes:

• The original file path of the file.

• The identified threat name (such as Backdoor:JS/Chopper.VH!MSR or Trojan:PowerShell/ReverseShell.SA).

• The timestamp of when the file was placed in quarantine (in UTC).

• The detection ThreatID, that can be used to correlate the quarantined file with other Windows Defender artifacts, such as the Windows Defender ETW events and Support log files.

More information on the data structures holding the metadata and how the quarantined files are stored can be found in FOX IT’s “Reverse, Reveal, Recover: Windows Defender Quarantine Forensics” blog post.

Tool(s)

The dissect functions defender.quarantine and defender.recover and the defender-dump.py Python script can be used to extract the metadata on the detections and the quarantined files.

# Retrieves the metadata on the detections from the "Quarantine\Entries" folder.
python3 defender-dump.py <SYSTEM_ROOT_DIR>
target-query <TARGET> -v -f defender.quarantine

# Extracts and decrypt the quarantined files from the "Quarantine\ResourceData" folder.
python3 defender-dump.py --dump <SYSTEM_ROOT_DIR>
target-query <TARGET> -v -f defender.recover -o <OUTPUT_FOLDER>

References

• FOX IT - Max Groot & Erik Schamper - Reverse, Reveal, Recover: Windows Defender Quarantine Forensics