2015-07 Security Bulletin: Junos: mbuf exhaustion due to sessions stuck in LAST_ACK state (CVE-2015-5358)
Product Affected:This issue can affect any product or platform running Junos OS.
Problem:When an active TCP connection transitions to LAST_ACK state and the daemon connected to the socket still has more data to send, the socket could get stuck in LAST_ACK state indefinitely, using up finite mbufs and connections. Triggering this condition repeatedly could lead to total mbuf exhaustion, requiring a reboot or switchover of the master RE to resolve.Exploitation of this issue requires establishment of a TCP connection to a listening port on the router. TCP ports protected by ingress and/or control plane firewall filters are not vulnerable to this issue. However, anti-spoofing mechanisms should be employed to protect against malicious attempts to bypass existing firewall filters. Juniper SIRT is not aware of any malicious exploitation of this vulnerability. This issue has been assigned CVE-2015-5358.
Solution:The following software releases have been updated to resolve this specific issue: Junos OS 12.1X44-D50, 12.1X46-D35, 12.1X47-D25, 12.3R9, 12.3X48-D15, 13.2R7, 13.2X51-D35, 13.2X52-D25, 13.3R6, 14.1R3-S2, 14.1R4, 14.1X53-D12, 14.1X53-D16, 14.1X55-D25, 14.2R2, 15.1R1, and all subsequent releases. This issue is being tracked as PR 1029758 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:Limit the exploitable attack surface of critical infrastructure networking equipment. Use access lists or firewall filters to limit access to the router via TCP only from trusted, administrative networks or hosts. Additionally, for BGP sessions, employ anti-spoofing mechanisms such as uRPF and TTL security mechanisms to protect against source address spoofing.
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. Modification History: 2015-07-08: Initial publication
Related Links: CVSS Score:CVSSv2: 7.1 (AV:N/AC:M/Au:N/C:N/I:N/A:C)
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.”