Windows Security 4663: Access to Microsoft Teams token and local storage files

Identifies non-Teams.exe processes accessing Microsoft Teams cookies or local storage objects on Windows (Event 4663).

FreeReviewedSigma · High · v2

Product: windows
Service: security
Author: @SerkinValery (SigmaHQ), DRL 1.1
Published: 2022-09-16
Updated: 2026-07-31

ATT&CK techniques

Cred Access

Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
- T1528Steal Application Access Token
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule flags Windows object access events where the accessed object name contains paths associated with Microsoft Teams cookies and Local Storage (leveldb). Adversaries may target these areas to obtain authentication/session tokens or persist via locally stored data. It relies on Security event 4663 telemetry and filters for accesses involving Teams.exe while matching the specific object name substrings.

Reporting behind it

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Possible VMware Workspace ONE SSRF via instanceHealth hostName At-Injection (via webserver)

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Windows Security 4663: Access to Microsoft Teams token and local storage files

Pivot detection · T1528 · 9 related

Changelog

v2
Candidate ingested via manual entry.2026-07-31
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.

windows-suspicious-access-to-microsoft-teams-token-and-local-storage-objects-466-25cde13e

title: "Windows Security 4663: Access to Microsoft Teams token and local storage files"
id: 1d2529ff-96a3-457b-96b4-e81c2267a66d
status: test
description: This rule flags Windows object access events where the accessed object name contains paths associated with Microsoft Teams cookies and Local Storage (leveldb). Adversaries may target these areas to obtain authentication/session tokens or persist via locally stored data. It relies on Security event 4663 telemetry and filters for accesses involving Teams.exe while matching the specific object name substrings.
references:
  - https://www.bleepingcomputer.com/news/security/microsoft-teams-stores-auth-tokens-as-cleartext-in-windows-linux-macs/
  - https://www.vectra.ai/blogpost/undermining-microsoft-teams-security-by-mining-tokens
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/builtin/security/win_security_teams_suspicious_objectaccess.yml
author: "@SerkinValery, Huntrule Team"
date: 2022-09-16
tags:
  - attack.credential-access
  - attack.t1528
logsource:
  product: windows
  service: security
detection:
  selection:
    EventID: 4663
    ObjectName|contains:
      - \Microsoft\Teams\Cookies
      - \Microsoft\Teams\Local Storage\leveldb
  filter:
    ProcessName|contains: \Microsoft\Teams\current\Teams.exe
  condition: selection and not filter
falsepositives:
  - Unknown
level: high
license: DRL-1.1
related:
  - id: 25cde13e-8e20-4c29-b949-4e795b76f16f
    type: derived

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