Apache Tomcat Native 1.2.0 to 1.2.16 and 1.1.23 to 1.1.34 has a flaw that does not properly check OCSP pre-produced responses, which are lists (multiple entries) of certificate statuses. Subsequently, revoked client certificates may not be properly identified, allowing for users to authenticate with revoked certificates to connections that require mutual TLS. Users not using OCSP checks are not affected by this vulnerability.
A vulnerability in Apache Tomcat Native could allow an authenticated, remote attacker to gain unauthorized access to a targeted system.
The vulnerability exists because the affected software improperly handles Online Certificate Status Protocol (OCSP) pre-produced responses. As a result, revoked certificates may not be properly identified. An attacker could exploit this vulnerability by using a revoked certificate to authenticate to a targeted system that uses a mutual Transport Layer Security (TLS) connection. A successful exploit could allow the attacker to gain unauthorized access to the system, which could be used to conduct further attacks.
Apache has confirmed the vulnerability and released software updates.
Administrators are advised to apply the appropriate updates.
Administrators are advised to allow only trusted users to have network access.
Administrators are advised to run both firewall and antivirus applications to minimize the potential of inbound and outbound threats.
Administrators may consider using IP-based access control lists (ACLs) to allow only trusted systems to access the affected systems.
Administrators can help protect affected systems from external attacks by using a solid firewall strategy.
Administrators are advised to monitor affected systems.
To exploit this vulnerability, the attacker must have user-level access to the targeted system. This access requirement may reduce the likelihood of a successful exploit.
Systems that are not using OCSP checks are not affected by this vulnerability.