A token tampering attack changes an API access token so flawed validation grants access the attacker should not have. JWTs carry user information and use signatures to protect integrity; accepting an improperly validated token can enable account hijacking and privilege escalation. section 4.4
Check the credential-validation process for these failure modes:
- Failing to validate a token signature correctly allows attackers to tamper with its contents. section 4.4
- Failing to reject expired tokens allows credentials to remain usable beyond their intended lifetime. section 4.4
- Distinguish tampering from credential replay: replay uses an intercepted, otherwise valid access token to impersonate its owner. section 4.4
Figure 4.5 A common broken authentication vulnerability is accepting unsigned or expired tokens.
Use the figure to inspect the central failure pattern: accepting unsigned or expired tokens. section 4.4
