CVE-2015-4000 – LOGJAM: TLS connections which support export grade DHE key-exchange are vulnerable to MITM attacks

https://notcve.org/view.php?id=CVE-2015-4000

The TLS protocol 1.2 and earlier, when a DHE_EXPORT ciphersuite is enabled on a server but not on a client, does not properly convey a DHE_EXPORT choice, which allows man-in-the-middle attackers to conduct cipher-downgrade attacks by rewriting a ClientHello with DHE replaced by DHE_EXPORT and then rewriting a ServerHello with DHE_EXPORT replaced by DHE, aka the "Logjam" issue. El protocolo TLS 1.2 y anteriores, cuando una suite de cifrado DHE_EXPORT está habilitada en un servidor pero no en un cliente, no transporta una elección DHE_EXPORT, lo que permite a atacantes man-in-the-middle realizar ataques de degradación del cifrado mediante la rescritura de un ClientHello con DHE remplazado por DHE_EXPORT y posteriormente la rescritura de un ServerHello con DHE_EXPORT remplazado por DHE, también conocido como el problema 'Logjam'. A flaw was found in the way the TLS protocol composes the Diffie-Hellman exchange (for both export and non-export grade cipher suites). An attacker could use this flaw to downgrade a DHE connection to use export-grade key sizes, which could then be broken by sufficient pre-computation. This can lead to a passive man-in-the-middle attack in which the attacker is able to decrypt all traffic. • http://aix.software.ibm.com/aix/efixes/security/sendmail_advisory2.asc http://fortiguard.com/advisory/2015-07-09-cve-2015-1793-openssl-alternative-chains-certificate-forgery http://ftp.netbsd.org/pub/NetBSD/security/advisories/NetBSD-SA2015-008.txt.asc http://h20564.www2.hpe.com/hpsc/doc/public/display?docId=emr_na-c04876402 http://h20564.www2.hpe.com/hpsc/doc/public/display?docId=emr_na-c04949778 http://kb.juniper.net/InfoCenter/index?page=content&id=JSA10681 http://kb.juniper.net/InfoC • CWE-310: Cryptographic Issues CWE-327: Use of a Broken or Risky Cryptographic Algorithm •