CVE-2015-1799

Description

A denial of service flaw was found in the way NTP hosts that were peering with each other authenticated themselves before updating their internal state variables. An attacker could send packets to one peer host, which could cascade to other peers, and stop the synchronization process among the reached peers.

Mitigation

To work around this issue, instead of configuring NTP hosts as peers with the 'peer' directive, use the 'server' directive on both hosts so that the connection uses a regular client/server mode of operation.

More information about how to configure NTP can be found at:

https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Deployment_Guide/ch-Configuring_NTP_Using_ntpd.html

Autokey authentication between NTP peers is not sufficient to fully mitigate this issue.

Common Vulnerability Scoring System (CVSS) Score Details

Info alert:Important note

CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).

CVSS v2 Score Breakdown

Red HatNVDcve.org
Base Score4.34.3N/A
Attack VectorNetworkAdjacent NetworkN/A
Access ComplexityMediumMediumN/A
AuthenticationNoneNoneN/A
Confidentiality ImpactNoneNoneN/A
Integrity ImpactNonePartialN/A
Availability ImpactPartialPartialN/A

Vector

Red Hat: AV:N/AC:M/Au:N/C:N/I:N/A:P

NVD: AV:A/AC:M/Au:N/C:N/I:P/A:P

Acknowledgements

This issue was discovered by Miroslav Lichvár (Red Hat).

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