CWE-551: Incorrect Behavior Order: Authorization Before Parsing and Canonicalization
If a web server does not fully parse requested URLs before it examines them for authorization, it may be possible for an attacker to bypass authorization protection.
How it's found
Incorrect Behavior Order: Authorization Before Parsing and Canonicalization 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.
For instance, the character strings /./ and / both mean current directory. If /SomeDirectory is a protected directory and an attacker requests /./SomeDirectory, the attacker may be able to gain access to the resource if /./ is not converted to / before the authorization check is performed.
Consequences
- Bypass Protection Mechanism
Mitigations
- Architecture and Design: URL Inputs should be decoded and canonicalized to the application's current internal representation before being validated and processed for authorization. Make sure that your application does not decode the same input twice. Such errors could be used to bypass allowlist schemes by introducing dangerous inputs after they have been checked.
Where this fits in a TurboPentest engagement
TurboPentest's agentic pentest is powerful and covers a broad range of issues automatically. This particular class is best confirmed in a manual IntegSec engagement, where human pentesters apply deeper methodology and a larger context window than any automated pass.
Frequently asked questions
What is CWE-551?
If a web server does not fully parse requested URLs before it examines them for authorization, it may be possible for an attacker to bypass authorization protection.
How do you find Incorrect Behavior Order: Authorization Before Parsing and Canonicalization?
Incorrect Behavior Order: Authorization Before Parsing and Canonicalization 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-551?
Bypass Protection Mechanism
Does TurboPentest test for Incorrect Behavior Order: Authorization Before Parsing and Canonicalization?
TurboPentest's agentic pentest is powerful and covers a broad range of issues automatically. This particular class is best confirmed in a manual IntegSec engagement, where human pentesters apply deeper methodology and a larger context window than any automated pass.
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