Bug 1363710 (CVE-2016-6301)

Summary: CVE-2016-6301 busybox: NTP server denial of service flaw
Product: [Other] Security Response Reporter: Martin Prpič <mprpic>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Status: CLOSED WONTFIX QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: admiller, dkholia, dvlasenk, mlichvar
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Fixed In Version: Doc Type: If docs needed, set a value
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2016-08-05 09:05:24 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Bug Depends On: 1363711    
Bug Blocks: 1363714    

Description Martin Prpič 2016-08-03 12:11:59 UTC
The busybox NTP implementation doesn't check the NTP mode of packets received on the server port and responds to any packet with the right size. This includes responses from another NTP server. An attacker can send a packet with a spoofed source address in order to create an infinite loop of responses between two busybox NTP servers. Adding more packets to the loop increases the traffic between the servers until one of them has a fully loaded CPU and/or network.

It seems this bug was actually inherited from openntpd, on which the busybox implementation was based on. In openntpd it was fixed in:


Busybox upstream patch:


Comment 1 Martin Prpič 2016-08-03 12:12:08 UTC

Name: Miroslav Lichvar (Red Hat)

Comment 2 Martin Prpič 2016-08-03 12:12:22 UTC
Created busybox tracking bugs for this issue:

Affects: fedora-all [bug 1363711]