CVE-2014-9296

La función de recepción en ntp_proto.c en ntpd en NTP anterior a 4.2.8 continúa ejecutando después de detectar un cierto error de autenticación, lo que podría permitir a un atacante remoto a provocar una asociación involuntaria mediante paquetes modificados.

A missing return statement in the receive() function could potentially allow a remote attacker to bypass NTP's authentication mechanism.

If no authentication key is defined in the ntp.conf file, a cryptographically-weak default key is generated. ntp-keygen before 4.2.7p230 uses a non-cryptographic random number generator with a weak seed to generate symmetric keys. A remote unauthenticated attacker may craft special packets that trigger buffer overflows in the ntpd functions crypto_recv() (when using autokey authentication), ctl_putdata(), and configure(). The resulting buffer overflows may be exploited to allow arbitrary malicious code to be executed with the privilege of the ntpd process. A section of code in ntpd handling a rare error is missing a return statement, therefore processing did not stop when the error was encountered. This situation may be exploitable by an attacker. Stephen Roettger of the Google Security Team, Sebastian Krahmer of the SUSE Security Team and Harlan Stenn of Network Time Foundation discovered that the length value in extension fields is not properly validated in several code paths in ntp_crypto.c, which could lead to information leakage or denial of service. Stephen Roettger of the Google Security Team reported that ACLs based on IPv6 ::1 addresses can be bypassed. The ntp package has been patched to fix these issues.