CWE-804: Guessable CAPTCHA | Glexia
CWE-804 (Guessable CAPTCHA) weakness overview with consequences, detection methods, mitigations, related CVEs and MITRE ATT&CK context.
Glexia's Take · Automated analysis
CWE-804: Guessable CAPTCHA
Guessable CAPTCHA represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Executive Impact
- Access Control Other: Bypass Protection Mechanism Other: When authorization, authentication, or another protection mechanism relies on CAPTCHA entities to ensure that only human actors can access certain functionality, then an automated attacker such as a bot may access the restricted functionality by guessing the CAPTCHA.
Developer Pattern
CWE-804 is the kind of defect developers can usually prevent with explicit validation, safer framework defaults, and tests that exercise hostile input or unsafe state transitions.
Automation confidence
high confidence from CWE-804, 4.20.
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Official CWE Definition
CWE-804: Guessable CAPTCHA
The product uses a CAPTCHA challenge, but the challenge can be guessed or automatically recognized by a non-human actor.
An automated attacker could bypass the intended protection of the CAPTCHA challenge and perform actions at a higher frequency than humanly possible, such as launching spam attacks. There can be several different causes of a guessable CAPTCHA: An audio or visual image that does not have sufficient distortion from the unobfuscated source image. A question is generated with a format that can be automatically recognized, such as a math question. A question for which the number of possible answers is limited, such as birth years or favorite sports teams. A general-knowledge or trivia question for which the answer can be accessed using a data base, such as country capitals or popular entertainers. Other data associated with the CAPTCHA may provide hints about its contents, such as an image whose filename contains the word that is used in the CAPTCHA.
Developer And Remediation Guidance
How teams prevent and detect this weakness
Causes
- Missing validation
- Unsafe defaults
- Insufficient authorization or memory-safety invariant
Remediation
- Use safe APIs
- Centralize the control
- Add regression tests
- Review logs and telemetry for attempted abuse
Detection
- Code review
- SAST
- DAST
- Focused regression tests
Mappings
Related CVEs, CWEs, and ATT&CK context
Related CWEs
ATT&CK Relevance
ATT&CK relevance is shown only when reviewed or responsibly inferred.