huntrule

Windows: Monitor access to Signal Desktop config.json and db.sqlite in AppData\Roaming

Alerts on unauthorized access attempts to Signal Desktop’s config.json (key) and db.sqlite (messages) in the default Roaming path.

FreeReviewedSigma · Medium · v2
Product
windows
Service
security
Author
Andreas Braathen (mnemonic.io) (SigmaHQ), DRL 1.1
Published
2025-10-19
Updated
2026-07-31
AnalysisDetection

ATT&CK techniques

Cred Access

  1. Recon

  2. Resource Dev

  3. Initial Access

  4. Execution

  5. Persistence

  6. Priv Esc

  7. Defense Evasion

  8. Cred Access

  9. Discovery

  10. Lateral Movement

  11. Collection

  12. C2

  13. Exfiltration

  14. Impact

What it detects

This rule flags Windows Security event 4663 for file access to Signal Desktop’s sensitive data files, specifically db.sqlite and config.json, under the default AppData\Roaming\Signal path. It matters because config.json contains the decryption key in plaintext, and db.sqlite stores locally saved messages, so access to both files can allow an attacker to decrypt message contents without the user’s credentials. The detection relies on audited file-system access events that include the accessed object name/type and are filtered to exclude accesses made by the Signal-related executables.

Reporting behind it

Related detections9 linkedT1003 — drag to rearrange
Malicious NTDS Credential Dump via Ntdsutil IFM Snapshot (via process_creation)
Suspicious Mimilite Credential Dumper Execution Writing KB-Named Output
Malicious InternalMonologue NTLM Downgrade Execution via process_creation
Suspicious Modification of msDS-KeyCredentialLink for Shadow Credential Abuse
Possible OxideHarvest Stealer Execution via Combined Short Flag Set
Suspicious Credential Dump Attempt via Task Manager (via process_creation)
Suspicious Ivanti EPMM Database Dump via mysqldump with .mifpp Credentials (via process_creation)
Suspicious Credential Dump via lsa.exe Debug Output
Malicious Wdigest Authentication Enabled - Reg via Command (via process_creation)
Windows: Monitor access to Signal Desktop config.json and db.sqlite in AppData\Roaming
Pivot detection · T1003 · 9 related

Changelog

v2
  1. v2
    Candidate ingested via manual entry.2026-07-31
  2. v1
    No changelog recorded for this version.2026-07-30

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.