Insecure TLS_KRB5_WITH_IDEA_CBC_MD5
- IANA name:
- TLS_KRB5_WITH_IDEA_CBC_MD5
- Hex code:
- 0x00, 0x25
- TLS Version(s):
- TLS1.0, TLS1.1, TLS1.2, TLS1.3
- Protocol:
- Transport Layer Security (TLS)
- Key Exchange:
- Kerberos 5 (KRB5)
- Authentication:
- Kerberos 5 (KRB5)
- Encryption:
- IDEA in Cipher Block Chaining mode (IDEA CBC)
- Hash:
- HMAC Message Digest 5 (MD5)
- Included in RFC:
- Machine-readable:
- application/json
This key exchange algorithm does not support Perfect Forward Secrecy (PFS) which is recommended, so attackers cannot decrypt the complete communication stream.
In 2013, researchers demonstrated a timing attack against several TLS implementations using the CBC encryption algorithm (see isg.rhul.ac.uk). Additionally, the CBC mode is vulnerable to plain-text attacks in TLS 1.0, SSL 3.0 and lower. A fix has been introduced with TLS 1.2 in form of the GCM mode which is not vulnerable to the BEAST attack. GCM should be preferred over CBC.
The Message Digest 5 algorithm suffers form multiple vulnerabilities and is considered insecure.