BEAST

Browser Exploit Against SSL/TLS

"The server is vulnerable to the BEAST attack."

Problem

The Browser Exploit Against SSL/TLS (BEAST) attack affects the SSL 2.0, SSL 3.0 and TLS 1.0 protocols, allowing a bad actor to decrypt the contents of an SSL-encrypted or TLS-encrypted session between a Web browser and a website. The attacker takes advantage of weakness in the block-based cipher suites.

This is a client-side attack where the attacker needs to control the "victims" browser. Most browsers are vulnerable to the BEAST attack.

In a BEAST attack, the attacker acts as a man-in-the-middle and uses specially-crafted plaintext input to decrypt the contents of an SSL-encrypted or TLS-encrypted session between a Web browser and a website. This type of attack allows the attacker to recover sensitive information (e.g., HTTP Authentication cookies).

Solution

Enable TLS 1.2 or TLS 1.3 on servers that support these protocols.
Enable TLS 1.2 or TLS 1.3 in Web browsers that support these protocols.

Workaround

Disable all block-based cipher suites in your server’s SSL/TLS configuration. Only use this workaround if you can't enable TLS 1.2 or TLS 1.3 on servers and in browsers.

Related warning

Problem

Solution

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