SSL_WEAK_CIPHER security protocol_error ai_generated true

TLS弱密码套件协商：服务器允许导出级密码导致降级攻击

TLS weak cipher suite negotiation: server allows export-grade ciphers enabling downgrade attack

ID: security/tls-weak-cipher-downgrade

其他格式: JSON · Markdown 中文 · English
88%修复率
87%置信度
1证据数
2023-03-01首次发现

版本兼容性

版本状态引入弃用备注
OpenSSL 1.1.1 active — — —
nginx 1.20.0 active — — —
Apache httpd 2.4.48 active — — —

根因分析

TLS服务器支持已弃用的密码套件（如EXPORT、DES、RC4）或允许协议降级至TLS 1.0/1.1，使中间人攻击者可以强制使用弱加密。

English

The TLS server supports deprecated cipher suites (e.g., EXPORT, DES, RC4) or allows protocol downgrade to TLS 1.0/1.1, enabling man-in-the-middle attackers to force weak encryption.

generic

官方文档

https://wiki.openssl.org/index.php/TLS_Downgrade_Protection

解决方案

  1. Disable all weak cipher suites and enforce TLS 1.2+ only. Example nginx config: ssl_protocols TLSv1.2 TLSv1.3; ssl_ciphers 'ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:...'; ssl_prefer_server_ciphers on;
  2. Use a tool like Mozilla SSL Configuration Generator to produce a hardened configuration, then test with sslyze or testssl.sh
  3. Enable TLS 1.3 support which mandates strong ciphers and provides downgrade protection via the ServerHello random value

无效尝试

常见但无效的做法:

  1. 70% 失败

    Weak ciphers like RC4 and DES are still supported in TLS 1.1 and 1.2, allowing downgrade.

  2. 90% 失败

    Does not fix the server configuration; attackers can use different IPs or proxies.

  3. 60% 失败

    HSTS only protects against SSL stripping, not cipher suite downgrade within the same protocol.