CWE-323: Reusing a Nonce, Key Pair in Encryption
Nonces should be used for the present occasion and only once.
How it's found
Reusing a Nonce, Key Pair in Encryption 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.
Consequences
- Bypass Protection Mechanism, Gain Privileges or Assume Identity: Potentially a replay attack, in which an attacker could send the same data twice, could be crafted if nonces are allowed to be reused. This could allow a user to send a message which masquerades as a valid message from a valid user.
Mitigations
- Implementation: Refuse to reuse nonce values.
- Implementation: Use techniques such as requiring incrementing, time based and/or challenge response to assure uniqueness of nonces.
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-323?
Nonces should be used for the present occasion and only once.
How do you find Reusing a Nonce, Key Pair in Encryption?
Reusing a Nonce, Key Pair in Encryption 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-323?
Bypass Protection Mechanism, Gain Privileges or Assume Identity: Potentially a replay attack, in which an attacker could send the same data twice, could be crafted if nonces are allowed to be reused. This could allow a user to send a message which masquerades as a valid message from a valid user.
Does TurboPentest test for Reusing a Nonce, Key Pair in Encryption?
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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