{
  "id": "security/tls-weak-cipher-downgrade",
  "signature": "TLS weak cipher suite negotiation: server allows export-grade ciphers enabling downgrade attack",
  "signature_zh": "TLS弱密码套件协商：服务器允许导出级密码导致降级攻击",
  "regex": "SSL.*weak cipher|TLS.*export.*cipher|Cipher suite.*not secure|SSL.*downgrade",
  "domain": "security",
  "category": "protocol_error",
  "subcategory": null,
  "root_cause": "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.",
  "root_cause_type": "generic",
  "root_cause_zh": "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。",
  "versions": [
    {
      "version": "OpenSSL 1.1.1",
      "introduced": null,
      "deprecated": null,
      "removed": null,
      "behavior_change": null,
      "status": "active"
    },
    {
      "version": "nginx 1.20.0",
      "introduced": null,
      "deprecated": null,
      "removed": null,
      "behavior_change": null,
      "status": "active"
    },
    {
      "version": "Apache httpd 2.4.48",
      "introduced": null,
      "deprecated": null,
      "removed": null,
      "behavior_change": null,
      "status": "active"
    }
  ],
  "os_specific": {},
  "dead_ends": [
    {
      "action": "",
      "why_fails": "Weak ciphers like RC4 and DES are still supported in TLS 1.1 and 1.2, allowing downgrade.",
      "fail_rate": 0.7,
      "condition": "",
      "sources": []
    },
    {
      "action": "",
      "why_fails": "Does not fix the server configuration; attackers can use different IPs or proxies.",
      "fail_rate": 0.9,
      "condition": "",
      "sources": []
    },
    {
      "action": "",
      "why_fails": "HSTS only protects against SSL stripping, not cipher suite downgrade within the same protocol.",
      "fail_rate": 0.6,
      "condition": "",
      "sources": []
    }
  ],
  "workarounds": [
    {
      "action": "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;",
      "success_rate": 0.95,
      "how": "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;",
      "condition": "",
      "sources": []
    },
    {
      "action": "Use a tool like Mozilla SSL Configuration Generator to produce a hardened configuration, then test with sslyze or testssl.sh",
      "success_rate": 0.9,
      "how": "Use a tool like Mozilla SSL Configuration Generator to produce a hardened configuration, then test with sslyze or testssl.sh",
      "condition": "",
      "sources": []
    },
    {
      "action": "Enable TLS 1.3 support which mandates strong ciphers and provides downgrade protection via the ServerHello random value",
      "success_rate": 0.85,
      "how": "Enable TLS 1.3 support which mandates strong ciphers and provides downgrade protection via the ServerHello random value",
      "condition": "",
      "sources": []
    }
  ],
  "workarounds_zh": [
    "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;",
    "Use a tool like Mozilla SSL Configuration Generator to produce a hardened configuration, then test with sslyze or testssl.sh",
    "Enable TLS 1.3 support which mandates strong ciphers and provides downgrade protection via the ServerHello random value"
  ],
  "transition_graph": {
    "leads_to": [],
    "preceded_by": [],
    "frequently_confused_with": []
  },
  "official_doc_url": "https://wiki.openssl.org/index.php/TLS_Downgrade_Protection",
  "official_doc_section": null,
  "error_code": "SSL_WEAK_CIPHER",
  "verification_tier": "ai_generated",
  "confidence": 0.87,
  "fix_success_rate": 0.88,
  "resolvable": "true",
  "first_seen": "2023-03-01",
  "last_confirmed": "2024-06-01",
  "last_updated": "2024-06-01",
  "evidence_count": 1,
  "tags": [],
  "locale": "en",
  "aliases": []
}