REDHAT-BUG-2359465: Medium severity MIT Kerberos vulnerability
Under specific configurations where RC4-HMAC-MD5 is negotiated for GSSAPI-secured communication, attackers can sniff messages and use MD5 collision techniques to craft altered messages that retain the same MIC (Message Integrity Code). The vulnerable checksum function from RFC4757 allows this due to its flawed use of MD5. The attack relies on RC4 being chosen over stronger encryption options and presumes attacker access to the network traffic.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Configuration
Update GSSAPI/Kerberos configuration so that RC4-HMAC-MD5 is not selected for the negotiated security context (avoid RC4 and the RFC4757 MD5-based vulnerable checksum/MIC construction).
GSSAPI-secured communication (e.g., Kerberos GSSAPI negotiation using RC4-HMAC-MD5) Cipher/MIC algorithm negotiation = Do not negotiate or use RC4-HMAC-MD5; prefer stronger encryption algorithms than RC4-HMAC-MD5 - Compensating control
Because the attack assumes attacker access to network traffic (sniffing), restrict and protect network paths used for GSSAPI-secured communication (e.g., isolate the network segment and limit access to only trusted hosts).
Event History
Frequently Asked Questions
What is the severity of REDHAT-BUG-2359465?
The severity of REDHAT-BUG-2359465 is considered critical due to the potential for message alteration.
What causes REDHAT-BUG-2359465?
REDHAT-BUG-2359465 is caused by the use of the vulnerable RC4-HMAC-MD5 configuration in GSSAPI-secured communications.
How do I fix REDHAT-BUG-2359465?
To fix REDHAT-BUG-2359465, upgrade to a version that disables the use of RC4-HMAC-MD5 for GSSAPI communications.
Who is affected by REDHAT-BUG-2359465?
Organizations using GSSAPI with RC4-HMAC-MD5 configurations for secure communication are affected by REDHAT-BUG-2359465.
What are the potential consequences of REDHAT-BUG-2359465?
The potential consequences of REDHAT-BUG-2359465 include unauthorized message alteration and security breaches.