SynopsisThe remote NTP server is affected by multiple vulnerabilities.
DescriptionThe version of the remote NTP server is 3.x or 4.x prior to 4.2.8p2.
It is, therefore, affected by the following vulnerabilities :
- The symmetric-key feature in the receive() function requires a correct message authentication code (MAC) only if the MAC field has a nonzero length. A man-in-the-middle attacker can exploit this to spoof packets by omitting the MAC. (CVE-2015-1798)
- A flaw exists in the symmetric-key feature in the receive() function when handling a specially crafted packet sent to one of two hosts that are peering with each other. An attacker can exploit this to cause the next attempt by the servers to synchronize to fail.
- A flaw exists in util/ntp-keygen.c due to the way that the ntp-keygen utility generates MD5 symmetric keys on big-endian systems. A remote attacker can exploit this to more easily guess MD5 symmetric keys and thereby spoof an NTP server or client. (CVE-2015-3405)
SolutionUpgrade to NTP version 4.2.8p2 or later.