webPromedium

LeadVault

hackadvisor

Task: Express.js CRM with OAuth 2.0 authentication and team-based data scoping. Solution: Abused unauthenticated client_credentials grant type (discovered via JS comments) to mint a service-account JWT that bypasses team filtering, revealing hidden system contact with flag in notes field.

jwt nodejs authentication_bypass information_disclosure nginx decoy_flag oauth2 client_credentials api_misconfiguration express_js team_scoping_bypass service_account

javascript_source_analysisdecoy_flag_avoidanceoauth_client_credentials_abuseunauthenticated_grant_typeservice_token_mintingteam_access_control_bypass

$ ls tags/ techniques/

jwt nodejs authentication_bypass information_disclosure nginx decoy_flag oauth2 client_credentials api_misconfiguration express_js team_scoping_bypass service_account

javascript_source_analysisdecoy_flag_avoidanceoauth_client_credentials_abuseunauthenticated_grant_typeservice_token_mintingteam_access_control_bypass

Analysis

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$ python3 exploit.py --target 192.168.1.1 --port 8080
[*] Connecting to target...
[+] Shell obtained!

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