Selection of Less-Secure Algorithm During Negotiation ('Algorithm Downgrade')

Opis

A protocol or its implementation supports interaction between multiple actors and allows those actors to negotiate which algorithm should be used as a protection mechanism such as encryption or authentication, but it does not select the strongest algorithm that is available to both parties.

When a security mechanism can be forced to downgrade to use a less secure algorithm, this can make it easier for attackers to compromise the product by exploiting weaker algorithm. The victim might not be aware that the less secure algorithm is being used. For example, if an attacker can force a communications channel to use cleartext instead of strongly-encrypted data, then the attacker could read the channel by sniffing, instead of going through extra effort of trying to decrypt the data using brute force techniques.

Skutki

• Access Control

  Bypass Protection Mechanism

Przykłady podatności

• CVE-2006-4302 Attacker can select an older version of the software to exploit its vulnerabilities.
• CVE-2006-4407 Improper prioritization of encryption ciphers during negotiation leads to use of a weaker cipher.
• CVE-2005-2969 chain: SSL/TLS implementation disables a verification step (CWE-325) that enables a downgrade attack to a weaker protocol.
• CVE-2001-1444 Telnet protocol implementation allows downgrade to weaker authentication and encryption using an Adversary-in-the-Middle AITM attack.
• CVE-2002-1646 SSH server implementation allows override of configuration setting to use weaker authentication schemes. This may be a composite with CWE-642.

Słabość nadrzędna

• CWE-693 Protection Mechanism Failure

Kiedy powstaje

• Architecture and Design — COMMISSION: This weakness refers to an incorrect design related to an architectural security tactic.

Dotyczy

Not Language-Specific

Uwagi

This is related to CWE-300, although not all downgrade attacks necessarily require an entity that redirects or interferes with the network. See examples.