Jakub Prokes

**Name of the Vulnerable Software and Affected Versions** NTP versions 4.x before 4.2.8p8 **Description** The issue allows remote attackers to cause a denial of service (ephemeral-association demobilization) by sending a spoofed crypto-NAK packet with incorrect authentication data at a certain time. Multiple Cisco products that incorporate a version of the Network Time Protocol daemon (ntpd) package are affected, which could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition or modify the time being advertised by a device acting as a Network Time Protocol (NTP) server. **Recommendations** For NTP versions 4.x before 4.2.8p8, update to version 4.2.8p8 or later to resolve the issue. As a temporary workaround, consider restricting access to the `ntpd` package to minimize the risk of exploitation. Avoid using the `crypto-NAK` packet in the affected NTP protocol until the issue is resolved. Restrict access to the vulnerable `ntpd` package to minimize the risk of exploitation.

**Name of the Vulnerable Software and Affected Versions** NTP versions 4.x before 4.2.8p8 **Description** The issue allows remote attackers to cause a denial of service (peer-variable modification) by sending spoofed packets from many source IP addresses in a certain scenario, as demonstrated by triggering an incorrect leap indication. This is related to the `process packet` function in `ntp proto.c` in `ntpd`. Multiple Cisco products that incorporate a version of the Network Time Protocol daemon (ntpd) package are also affected, potentially allowing an unauthenticated, remote attacker to cause a denial of service (DoS) condition or modify the time being advertised by a device acting as a Network Time Protocol (NTP) server. **Recommendations** For NTP versions 4.x before 4.2.8p8, update to version 4.2.8p8 or later to resolve the issue. As a temporary workaround, consider restricting access to the `process packet` function in `ntp proto.c` until a patch is available. For Cisco products, apply the software updates that address these vulnerabilities when they become available. Workarounds that address one or more of these vulnerabilities may be available and will be documented in the Cisco bug for each affected product.