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AUSCERT External Security Bulletin Redistribution
ESB-2013.0966
2013-07 Security Bulletin: Junos: Kernel crash during processing of certain
ARP requests when proxy-arp and arp-resp options enabled (CVE-2013-4686)
12 July 2013
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AusCERT Security Bulletin Summary
---------------------------------
Product: kernel
Publisher: Juniper Networks
Operating System: Juniper
Impact/Access: Denial of Service -- Remote/Unauthenticated
Resolution: Patch/Upgrade
CVE Names: CVE-2013-4686
Original Bulletin:
http://kb.juniper.net/InfoCenter/index?page=content&id=JSA10576
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2013-07 Security Bulletin: Junos: Kernel crash during processing of certain ARP
requests when proxy-arp and arp-resp options enabled (CVE-2013-4686)
[JSA10576] Hide KB Properties
Categories:
Switch Products
Security Products
Router Products
JUNOS
SIRT Advisory
Security Advisories ID: JSA10576
Last Updated: 10 Jul 2013
Version: 2.0
PRODUCT AFFECTED:
This issue can affect any product or platform running Junos OS 10.4, 11.4,
11.4X27, 12.1X44, 12.1, 12.2, or 12.3
PROBLEM:
The Junos kernel may crash when receiving a certain ARP request from a client
when a 'family inet' interface:
- - is configured as a VLAN interface with an unnumbered address based on lo0
- - lo0 is configured with a non-/32 address, and
- - both 'proxy-arp unrestricted' and 'arp-resp unrestricted' are enabled
An example affected configuration is shown below:
interfaces {
ge-3/0/0 {
interface-transmit-statistics;
flexible-vlan-tagging;
encapsulation flexible-ethernet-services;
unit 4000 {
arp-resp unrestricted;
proxy-arp unrestricted;
vlan-tags outer 1 inner 4000;
family inet {
mac-validate strict;
unnumbered-address lo0.0;
}
}
}
lo0 {
unit 0 {
family inet {
address 10.0.0.1/24;
}
}
}
ge-3/1/0 {
unit 0 {
family inet {
address 20.0.0.2/24;
address 10.0.0.4/31;
}
}
}
}
routing-options {
static {
route 11.0.0.0/24 next-hop 20.0.0.1;
}
}
This issue was found during internal product security testing.
Juniper SIRT is not aware of any malicious exploitation of this vulnerability.
No other Juniper Networks products or platforms are affected by this issue.
This issue has been assigned CVE-2013-4686.
SOLUTION:
All Junos OS software releases built on or after 2013-06-09 have fixed this
specific issue. Releases containing the fix specifically include: 10.4R14,
11.4R8, 11.4X27.43 (BBE), and 12.1X44-D20 (SRX), 12.1R6, 12.2R4, 12.3R2,
13.1R1, and all subsequent releases (i.e. all releases built after 13.1R1).
Customers can confirm the build date of any Junos OS release by issuing the
command 'show version detail'.
This issue is being tracked as PR 842091 and is visible on the Customer
Support website.
KB16765 - "In which releases are vulnerabilities fixed?" describes which
release vulnerabilities are fixed as per our End of Engineering and End of
Life support policies.
WORKAROUND:
If the 'arp-resp unrestricted' and/or 'proxy-arp unrestricted' options are not
required, removing either configuration statement will completely mitigate
this kernel crash. Additionally, if there is no specific need to use a non-/32
address on the lo0 interface, changing the mask to /32 will also mitigate this
issue.
IMPLEMENTATION:
How to obtain fixed software:
Security vulnerabilities in Junos are fixed in the next available Maintenance
Release of each supported Junos version. In some cases, a Maintenance Release
is not planned to be available in an appropriate time-frame. For these cases,
Service Releases are made available in order to be more timely. Security
Advisory and Security Notices will indicate which Maintenance and Service
Releases contain fixes for the issues described. Upon request to JTAC,
customers will be provided download instructions for a Service Release.
Although Juniper does not provide formal Release Note documentation for a
Service Release, a list of "PRs fixed" can be provided on request.
RELATED LINKS:
- - KB16613: Overview of the Juniper Networks SIRT Monthly Security Bulletin
Publication Process
- - KB16765: In which releases are vulnerabilities fixed?
- - KB16446: Common Vulnerability Scoring System (CVSS) and Juniper's Security
Advisories
- - Report a Vulnerability - How to Contact the Juniper Networks Security
Incident Response Team
- - CVE-2013-4686: Kernel crash during processing of certain ARP requests when
proxy-arp and arp-resp options enabled
CVSS SCORE:
7.1 (AV:N/AC:M/Au:N/C:N/I:N/A:C)
RISK LEVEL:
High
RISK ASSESSMENT:
Information for how Juniper Networks uses CVSS can be found at KB 16446
"Common Vulnerability Scoring System (CVSS) and Juniper's Security Advisories."
ACKNOWLEDGEMENTS:
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