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2012-07 Security Bulletin: Junos: Kernel crash due to ICMPv6 packet with corrupted payload

  [JSA10518] Show Article Properties


Legacy Advisory Id:
PSN-2012-07-644
Product Affected:
This issue can affect all Junos routers configured for VPNv6 running Junos OS 10.4 or later.
Problem:

Upon receipt of an ICMPv6 packet with an MPLS TTL=1 and a specifically corrupted payload within a IPv6 L3VPN, the Junos kernel may crash with the following message:
panic: rn_clone_unwire parent unreferenced
Only VPNv6 configurations without the 'vrf-table-label' statement in the routing instance configuration are affected. Additionally, this issue does not affect 6PE deployments.

This issue only affects Junos 10.4 and above. Releases prior to Junos 10.4 are unaffected by this vulnerability.

Juniper SIRT is not aware of any malicious exploitation of this vulnerability.

No other Juniper Networks products or platforms are affected by this issue.
Solution:

Additional checks and validation were added to the IPv6 code to insure that payload corruption would not cause a kernel panic.

All Junos OS software releases built on or after 2012-06-21 have fixed this specific issue. Releases containing the fix specifically include: 10.4S10, 11.4R3-S2, 11.4R4, 12.1R1, and all subsequent releases (i.e. all releases built after 12.1R1).

This issue is being tracked as PR 697848 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:

  • Enable 'no-propagate-ttl' or 'no-decrement-ttl' as appropriate to avoid MPLS TTL expirations from reaching the RE.
  • Include the 'vrf-table-label' statement in the configuration of VRF routing tables.
  • If neither option is acceptable for your environment, a temporary workaround to avoid processing that leads to the rpd crash would be to set the sysctl variable net.tag.icmpreply to 0.
    Please note that sysctl variable changes do not survive RE reboots or switchovers, and are reset when routing configuration changes are performed.
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:
CVSS Score:
5.4 (AV:N/AC:H/Au:N/C:N/I:N/A:C)
Severity Level:
Medium
Severity Assessment:
Information for how Juniper Networks uses CVSS can be found at KB 16446 "Common Vulnerability Scoring System (CVSS) and Juniper's Security Advisories."