[arch-security] [ASA-201504-9] chrony: denial of service
Christian Rebischke
chris.rebischke at gmail.com
Wed Apr 8 18:11:02 UTC 2015
Arch Linux Security Advisory ASA-201504-9
=========================================
Severity: Medium
Date : 2015-04-08
CVE-ID : CVE-2015-1853
Package : chrony
Type : denial of service
Remote : Yes
Link : https://wiki.archlinux.org/index.php/CVE
Summary
=======
The package chrony before version 1.31.1-1 is vulnerable to denial of service
Resolution
==========
Upgrade to 1.31.1-1
# pacman -Syu "chrony>=1.31.1-1"
The problem has been fixed upstream.
Workaround
==========
None.
Description
===========
CVE-2015-1853 (denial of service):
This issue is similiar to the "ntp CVE-2015-1799"-issue.
An attacker knowing that NTP hosts A and B are peering with each other
(symmetric association) can send a packet to host A with source address of B
which will set the NTP state variables on A to the values sent by the attacker.
Host A will then send on its next poll to B a packet with originate timestamp
that doesn't match the transmit timestamp of B and the packet will be dropped.
If the attacker does this periodically for both hosts, they won't be able to
synchronize to each other. This is a known denial-of-service attack
Impact
======
CVE-2015-1853 (denial of service):
An attacker could stop the synchronizing process of chrony.
References
==========
https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2015-1853
https://access.redhat.com/security/cve/CVE-2015-1853
http://seclists.org/oss-sec/2015/q2/63
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