Detection rules › Sigma

Potentially Suspicious Command Targeting Teams Sensitive Files

Status
test
Severity
medium
Log source
product windows, category process_creation
Author
@SerkinValery
Source
github.com/SigmaHQ/sigma

Detects a commandline containing references to the Microsoft Teams database or cookies files from a process other than Teams. The database might contain authentication tokens and other sensitive information about the logged in accounts.

MITRE ATT&CK coverage

TacticTechniques
Credential AccessT1528 Steal Application Access Token

Event coverage

Rule body yaml

title: Potentially Suspicious Command Targeting Teams Sensitive Files
id: d2eb17db-1d39-41dc-b57f-301f6512fa75
status: test
description: |
    Detects a commandline containing references to the Microsoft Teams database or cookies files from a process other than Teams.
    The database might contain authentication tokens and other sensitive information about the logged in accounts.
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
author: '@SerkinValery'
date: 2022-09-16
modified: 2023-12-18
tags:
    - attack.credential-access
    - attack.t1528
logsource:
    product: windows
    category: process_creation
detection:
    selection:
        CommandLine|contains:
            - '\Microsoft\Teams\Cookies'
            - '\Microsoft\Teams\Local Storage\leveldb'
    filter_main_legit_locations:
        Image|endswith: '\Microsoft\Teams\current\Teams.exe'
    condition: selection and not 1 of filter_main_*
falsepositives:
    - Unknown
level: medium

Stages and Predicates

Stage 0: condition

selection and not 1 of filter_main_*

Stage 1: selection

selection:
    CommandLine|contains:
        - '\Microsoft\Teams\Cookies'
        - '\Microsoft\Teams\Local Storage\leveldb'

Stage 2: not filter_main_legit_locations

filter_main_legit_locations:
    Image|endswith: '\Microsoft\Teams\current\Teams.exe'

Exclusions

Top-level NOT(...) conjuncts: predicates this rule actively suppresses.

FieldKindExcluded values
Imageends_with\Microsoft\Teams\current\Teams.exe

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

FieldKindValues
CommandLinematch
  • \Microsoft\Teams\Cookies
  • \Microsoft\Teams\Local Storage\leveldb