Potentially Suspicious JWT Token Search Via CLI

Severity: medium
Author: Nasreddine Bencherchali (Nextron Systems), kagebunsher
Source: upstream

Detects potentially suspicious search for JWT tokens via CLI by looking for the string "eyJ0eX" or "eyJhbG". JWT tokens are often used for access-tokens across various applications and services like Microsoft 365, Azure, AWS, Google Cloud, and others. Threat actors may search for these tokens to steal them for lateral movement or privilege escalation.

MITRE ATT&CK coverage

Tactic	Techniques
Credential Access	`T1528` Steal Application Access Token, `T1552.001` Unsecured Credentials: Credentials In Files

Event coverage

Provider	Event ID	Title
Sysmon	1	Process creation
Security-Auditing	4688	A new process has been created.

Stages and Predicates

Stage 1: `all of selection_tools`

or:
CommandLine|contains: 'find '
CommandLine|contains: find.exe
CommandLine|contains: findstr
CommandLine|contains: 'select-string '
CommandLine|contains: strings

Stage 2: `all of selection_jwt_string`

or:
CommandLine|contains: ' ''eyJ0eX'''
CommandLine|contains: ' ''eyJhbG'''
CommandLine|contains: ' "eyJ0eX"'
CommandLine|contains: ' "eyJhbG"'
CommandLine|contains: ' eyJ0eX'
CommandLine|contains: ' eyJhbG'
CommandLine|contains: eyJ0eXAiOi
CommandLine|contains: eyJhbGciOi

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.

Field	Kind	Values
`CommandLine`	match	`"eyJ0eX"` `"eyJhbG"` `'eyJ0eX'` `'eyJhbG'` `eyJ0eX` `eyJhbG` `eyJ0eXAiOi` `eyJhbGciOi` `find` `find.exe` `findstr` corpus 3 (sigma 3) `select-string` `strings`