CVE-2014-9295

Múltiples desbordamientos de buffer en ntpd en NTP anterior a 4.2.8, permite a atacantes remotos la ejecución de código arbitrario mediante un paquete manipulado, relacionado con (1) la función crypto_recv cuando se utiliza la característica Autokey Authentication, (2) la función ctl_putdata y (3) la función de configuración.

Multiple buffer overflow flaws were discovered in ntpd's crypto_recv(), ctl_putdata(), and configure() functions. A remote attacker could use either of these flaws to send a specially crafted request packet that could crash ntpd or, potentially, execute arbitrary code with the privileges of the ntp user. Note: the crypto_recv() flaw requires non default configurations to be active, while the ctl_putdata() flaw, by default, can only be exploited via local attackers, and the configure() flaw requires additional authentication to exploit.

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.