Vulnerabilities in SSL & TLS :- Logjam

Main Points

• For this attack to work, the attacker must use a different exploit to become a person-in-the-middle and inject content into the network traffic stream.
• Very similar to FREAK except this time, Diffie-Hellman is used instead of RSA.
• Diffie-Hellman key exchange is a popular cryptographic algorithm that allows Internet protocols to agree on a shared key and negotiate a secure connection. It is essential to many protocols, including HTTPS, SSH, IPsec, SMTPS, and those that rely on TLS.
• The Logjam vulnerability allows a person-in-the-middle attacker to downgrade vulnerable TLS connections to 512-bit export-grade cryptography.

Quick Reference

Description

The SSL Logjam vulnerability allows attackers within person-in-the-middle context to exposes Export Grade cipher suites to downgrade TLS connections.

Name

Logjam

CVE Number

Closest thing to an official CVE number is CVE-2015-4000.

Type of Vulnerability

Method for attacking Die-Hellman (DH) key exchange

Affected

The TLS protocol 1.2 and earlier when a DHE_EXPORT cipher suite is enabled.

Remediation

Disable support for export cipher suites and use a 2048-bit Diffie-Hellman group.