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:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED WONTFIX	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	admiller, dkholia, dvlasenk, mlichvar
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
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:
Embargoed:
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:

https://github.com/openntpd-portable/openntpd-openbsd/commit/28a2f904aafbf4c209fe6fa04ffb9308740fd78a

Busybox upstream patch:

https://git.busybox.net/busybox/commit/?id=150dc7a2b483b8338a3e185c478b4b23ee884e71

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

Acknowledgments:

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]