Ubuntu Security Notice 2449-1 – Neel Mehta discovered that NTP generated weak authentication keys. A remote attacker could possibly use this issue to brute force the authentication key and send requests if permitted by IP restrictions. Stephen Roettger discovered that NTP generated weak MD5 keys. A remote attacker could possibly use this issue to brute force the MD5 key and spoof a client or server. Stephen Roettger discovered that NTP contained buffer overflows in the crypto_recv(), ctl_putdata() and configure() functions. In non-default configurations, a remote attacker could use these issues to cause NTP to crash, resulting in a denial of service, or possibly execute arbitrary code. The default compiler options for affected releases should reduce the vulnerability to a denial of service. In addition, attackers would be isolated by the NTP AppArmor profile. Various other issues were also addressed.