CWE-206: Observable Internal Behavioral Discrepancy
The product performs multiple behaviors that are combined to produce a single result, but the individual behaviors are observable separately in a way that allows attackers to reveal internal state or internal decision points.
How it's found
Observable Internal Behavioral Discrepancy is a specific, narrowly defined instance of a broader pattern. Testers confirm it with targeted code review and a proof-of-concept input that exercises the exact code path this weakness describes.
Ideally, a product should provide as little information as possible to an attacker. Any hints that the attacker may be making progress can then be used to simplify or optimize the attack. For example, in a login procedure that requires a username and password, ultimately there is only one decision: success or failure. However, internally, two separate actions are performed: determining if the username exists, and checking if the password is correct. If the product behaves differently based on whether the username exists or not, then the attacker only needs to concentrate on the password.
Consequences
- Read Application Data, Bypass Protection Mechanism
Mitigations
- Setup generic response pages for error conditions. The error page should not disclose information about the success or failure of a sensitive operation. For instance, the login page should not confirm that the login is correct and the password incorrect. The attacker who tries random account name may be able to guess some of them. Confirming that the account exists would make the login page more susceptible to brute force attack.
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-206?
The product performs multiple behaviors that are combined to produce a single result, but the individual behaviors are observable separately in a way that allows attackers to reveal internal state or internal decision points.
How do you find Observable Internal Behavioral Discrepancy?
Observable Internal Behavioral Discrepancy is a specific, narrowly defined instance of a broader pattern. Testers confirm it with targeted code review and a proof-of-concept input that exercises the exact code path this weakness describes.
What is the impact of CWE-206?
Read Application Data, Bypass Protection Mechanism
Does TurboPentest test for Observable Internal Behavioral Discrepancy?
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.
Related CWEs
About this reference
These security references are maintained by IntegSec, an offensive-security firm whose team holds CISSP, OSCP, and OSCE certifications and has run thousands of penetration tests. Content is kept current as tools, standards, and attack techniques evolve.
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