CWE-757: Selection of Less-Secure Algorithm During Negotiation ('Algorithm Downgrade')
CWE版本: 4.18
更新日期: 2025-09-09
弱点描述
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.
扩展描述
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.
常见后果
影响范围: Access Control
技术影响: Bypass Protection Mechanism
检测方法
方法: Automated Static Analysis
Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)
有效性: High
观察示例
参考: CVE-2006-4302
Attacker can select an older version of the software to exploit its vulnerabilities.
参考: CVE-2006-4407
Improper prioritization of encryption ciphers during negotiation leads to use of a weaker cipher.
参考: CVE-2005-2969
chain: SSL/TLS implementation disables a verification step (CWE-325) that enables a downgrade attack to a weaker protocol.
参考: CVE-2001-1444
Telnet protocol implementation allows downgrade to weaker authentication and encryption using an Adversary-in-the-Middle AITM attack.
参考: CVE-2002-1646
SSH server implementation allows override of configuration setting to use weaker authentication schemes. This may be a composite with CWE-642.
引入模式
| 阶段 | 说明 |
|---|---|
| Architecture and Design | COMMISSION: This weakness refers to an incorrect design related to an architectural security tactic. |
关键信息
CWE ID: CWE-757
抽象级别: Base
结构: Simple
状态: Incomplete