CWE-603: Use of Client-Side Authentication
A client/server product performs authentication within client code but not in server code, allowing server-side authentication to be bypassed via a modified client that omits the authentication check.
How it's found
Use of Client-Side Authentication is typically found by tracing untrusted input from where it enters the system to the point where it is used without the check or neutralization this weakness describes, combining manual code review with dynamic testing.
Client-side authentication is extremely weak and may be breached easily. Any attacker may read the source code and reverse-engineer the authentication mechanism to access parts of the application which would otherwise be protected.
Consequences
- Bypass Protection Mechanism, Gain Privileges or Assume Identity
Mitigations
- Architecture and Design: Do not rely on client side data. Always perform server side authentication.
Where this fits in a TurboPentest engagement
This weakness is not covered by the automated black-box pentest. IntegSec pentesters cover it in a manual engagement.
Frequently asked questions
What is CWE-603?
A client/server product performs authentication within client code but not in server code, allowing server-side authentication to be bypassed via a modified client that omits the authentication check.
How do you find Use of Client-Side Authentication?
Use of Client-Side Authentication is typically found by tracing untrusted input from where it enters the system to the point where it is used without the check or neutralization this weakness describes, combining manual code review with dynamic testing.
What is the impact of CWE-603?
Bypass Protection Mechanism, Gain Privileges or Assume Identity
Does TurboPentest test for Use of Client-Side Authentication?
This weakness is not covered by the automated black-box pentest. IntegSec pentesters cover it in a manual engagement.
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Written and reviewed by
Michel Chamberland - Founder & CEO, IntegSec
CISSP, OSCP, OSCE, CEH, GIAC, CCSK · 20+ years in offensive security
Michel has spent 20+ years on offensive security teams including IBM X-Force Red and Trustwave SpiderLabs, leading penetration tests, red team engagements, and breach response for Fortune 500 customers. He is the founder of IntegSec and the architect of TurboPentest.
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