Weak TLS_KRB5_WITH_3DES_EDE_CBC_SHA
- IANA name:
- TLS_KRB5_WITH_3DES_EDE_CBC_SHA
- Hex code:
- 0x00, 0x1F
- 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:
- Triple-DES (Encrypt Decrypt Encrypt) in Cipher Block Chaining mode (3DES EDE CBC)
- Hash:
- HMAC Secure Hash Algorithm 1 (SHA)
- 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.
While Triple-DES is still recognized as a secure symmetric-key encryption, a more and more standardizations bodies and projects decide to deprecate this algorithm. Though not broken, it has been proven to suffer from several vulnerabilities in the past (see sweet32.info).
The Secure Hash Algorithm 1 has been proven to be insecure as of 2017 (see shattered.io).