如何解決 TLS/SSL 使用了不安全的加密演演算法: ARCFOUR、CBC、HMAC-MD5、HMAC-RIPEMD160

弱點掃瞄

弱點: TLS Service Supports Weak Cipher Suite

Transport Layer Security (TLS), the successor to Secure Socket Layer (SSL), is a network protocol that encrypt communications between TLS servers (e.g., websites) and TLS clients (e.g., web browsers). Every communication is secured by a cipher suite: a combination of several algorithms working in concert. Cryptographic algorithms do not have a defined lifetime, but academics, researchers, and nation states are constantly evaluating them for weaknesses. Consensus on which algorithms are untrustworthy evolves over time, and if a communication is protected with a weak cipher suite then that communication can be altered or decrypted.

Severity: Medium
Risk: A TLS service was observed supporting weak cipher suites.
Recommendation: Disable the cipher suites listed in the evidence column of the measurement.

解決方法

說明

與這一篇的內容相似，關閉 SSL/TLS 中不安全的演演算法即可。

執行步驟

[Web Server (Apache)]

編輯 /etc/httpd/conf.d/ssl.conf，修改 SSLCipherSuite 參數如下:

SSLCipherSuite "EECDH+ECDSA+AESGCM EECDH+aRSA+AESGCM EECDH+ECDSA+SHA384 EECDH+ECDSA+SHA256 EECDH+aRSA+SHA384 EECDH+aRSA+SHA256 !EECDH+aRSA+RC4 EECDH EDH+aRSA !RC4 !aNULL !eNULL !LOW !3DES !MD5 !EXP !PSK !SRP !DSS !EDH-RSA-DES-CBC3-SHA !ECDHE-RSA-DES-CBC3-SHA !DES-CBC3-SHA !ECDHE-RSA-RC4-SHA !RC4-MD5 !RC4-SHA"

2. 重新啟動 Apache:

$ service httpd restart

[Mail Server (Devecot)]

1. 編輯 /etc/dovecot/conf.d/10-ssl.conf，修改 ssl_cipher_list 參數如下:

ssl_cipher_list = kEECDH:+kEECDH+SHA:kEDH:+kEDH+SHA:+kEDH+CAMELLIA:kECDH:+kECDH+SHA:kRSA:+kRSA+SHA:+kRSA+CAMELLIA:!aNULL:!eNULL:!SSLv2:!RC4:!MD5:!DES:!EXP:!SEED:!IDEA:!3DES

2. 重新啟動 Dovecot:

$ service dovecot restart

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