CVE-2014-9293

La función config_auth en ntpd en NTP anterior a 4.2.7p11, cuando no se configura una clave de autenticación, incorréctamente genera una clave, esto hace que atacantes remotos puedan romper los mecanismos de protección fácilmente mediante un ataque de fuerza bruta.

It was found that ntpd automatically generated weak keys for its internal use if no ntpdc request authentication key was specified in the ntp.conf configuration file. A remote attacker able to match the configured IP restrictions could guess the generated key, and possibly use it to send ntpdc query or configuration requests.

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.