Sigma rule: File Access Of Signal Desktop Sensitive Data

A detection rule from the SigmaHQ repository, shown as its author published it. Dataset version ref-9690c6c64454, updated 2025-10-19T00:00:00.000Z.

Rule

Title: File Access Of Signal Desktop Sensitive Data
Status: experimental
Level: medium
Author: Andreas Braathen (mnemonic.io)
Date: 2025-10-19
File: rules/windows/builtin/security/win_security_signal_sensitive_config_access.yml
Commit: ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects access to Signal Desktop's sensitive data files: db.sqlite and config.json.
The db.sqlite file in Signal Desktop stores all locally saved messages in an encrypted SQLite database, while the config.json contains the decryption key needed to access that data.
Since the key is stored in plain text, a threat actor who gains access to both files can decrypt and read sensitive messages without needing the users credentials.
Currently the rule only covers the default Signal installation path in AppData\Roaming. Signal Portable installations may use different paths based on user configuration. Additional paths can be added to the selection as needed.

Log source

product: windows
service: security
definition: Requirements: System Access Control List (SACL) policy with attributes List folder/read data on Objects

Detection

selection:
    EventID: 4663
    ObjectType: 'File'
    ObjectName|contains: '\AppData\Roaming\Signal\'
    ObjectName|endswith:
        - '\config.json'
        - '\db.sqlite'
filter_main_signal:
    ProcessName|endswith:
        - '\signal-portable.exe'
        - '\signal.exe'
condition: selection and not 1 of filter_main_*

False positives (as the rule lists them)

Unlikely, but possible from AV or backup software accessing the files.

MITRE ATT&CK ids this rule names

T1003

References

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/builtin/security/win_security_signal_sensitive_config_access.yml

Sources and licences

SigmaHQ
"File Access Of Signal Desktop Sensitive Data" by Andreas Braathen (mnemonic.io) (SigmaHQ). Rule: https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/builtin/security/win_security_signal_sensitive_config_access.yml.
Licensed under the Detection Rule License (DRL) 1.1: https://github.com/SigmaHQ/Detection-Rule-License
Detection Rule License (DRL) 1.1

Cite this page

Dragons Eye Ransomware Tracker, "Sigma rule: File Access Of Signal Desktop Sensitive Data",
entity page, dataset version ref-9690c6c64454, updated 2025-10-19T00:00:00.000Z,
https://ransomware-tracker.com/detections/sigma/5d6c375a-18ae-4952-b4f6-8b803f6c8555 (accessed 2026-11-03).
Underlying source: SigmaHQ rule 5d6c375a-18ae-4952-b4f6-8b803f6c8555, commit ccbb0369507f796db0b0ae6854c8a2be471b9d84.

Pages change. The dataset version identifies the data, but no archive of old versions is kept, so this citation cannot be replayed later.