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Components
B
Key Exchange Method
Name
Kerberos V5 (KRB5)
Security
A Kerberos[220][221][222][223][224][225][226] cipher suite[471][472]s provide secure communication where the authentication and the establishment of a master secret will be done using the client's Kerberos credentials while client and server are mutually authenticated. The Kerberos protocol is considered secure, however it's authentication model is vulnerable to brute-force attack[555] against the key distribution center[44] and there are some protocol specific attacks [530][531]. Leading client applications do not use this algorithm. Unless your application or requirements specifically call for their use, it is generally safer to avoid cipher suites that are not adopted and supported by a critical mass of the industry.
Recommendations
If your application or requirements specifically call for the use of algorithms which are not used by the leading client applications set the cipher suite order explicitly and cipher suites used by the leading client applications be preferred over the ones which do not used by them.
B
Authentication Method
Name
Kerberos V5 (KRB5)
Security
A Kerberos[220][221][222][223][224][225][226] cipher suite[471][472]s provide secure communication where the authentication and the establishment of a master secret will be done using the client's Kerberos credentials while client and server are mutually authenticated. The Kerberos protocol is considered secure, however it's authentication model is vulnerable to brute-force attack[555] against the key distribution center[44] and there are some protocol specific attacks [530][531]. Leading client applications do not use this algorithm. Unless your application or requirements specifically call for their use, it is generally safer to avoid cipher suites that are not adopted and supported by a critical mass of the industry.
Recommendations
If your application or requirements specifically call for the use of algorithms which are not used by the leading client applications set the cipher suite order explicitly and cipher suites used by the leading client applications be preferred over the ones which do not used by them.
F
Encryption Type
Name
RC4-128
Security
Encryption algorithm Rivest Cipher 4[459][460][461][462] is a stream cipher[78][79] that is more malleable[158] than a block cipher[524][525][526][527]. It has multiple vulnerabilities[27][28][29][30][31] (eg: related-key attack[53], distinguishing attack[349], ...), so attacker can apply statistical analysis against it to recover the encrypted text.
Recommendations
Remove the cipher suite from the list of cipher suites supported by your server.
A+
Encryption Key Size
Name
128
Security
The symmetric key[193][194][195] withkey size[438] more than 128 bits as it is should be according to National Institute of Standards and Technology[428][429] so it is not vulnerable to preimage attack[215] and it cannreliably prove that message came from the stated sender (its authenticity) and has not been changed, so connection is not open for a man-in-the-middle attack[414].
Recommendations
Remove the cipher suite from the list of cipher suites supported by your server.
