Cisco Security Advisory
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CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L/E:X/RL:X/RC:X
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A vulnerability in the IPsec packet processor of Cisco IOS XR Software could allow an unauthenticated remote attacker to cause a denial of service (DoS) condition for IPsec sessions to an affected device.
The vulnerability is due to improper handling of packets by the IPsec packet processor. An attacker could exploit this vulnerability by sending malicious ICMP error messages to an affected device that get punted to the IPsec packet processor. A successful exploit could allow the attacker to deplete IPsec memory, resulting in all future IPsec packets to an affected device being dropped by the device. Manual intervention is required to recover from this situation.
Cisco has released software updates that address the vulnerability described in this advisory. There are workarounds that address this vulnerability.
This advisory is available at the following link:
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxr-ipsec-dos-q8UPX6m
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Vulnerable Products
At the time of publication, this vulnerability affected Cisco IOS XR Software release prior to 6.4.3, 6.6.3, 7.0.2 and 7.1.1, respectively, that have the IPsec process ipsec_mp or ipsec_pp running. Both IPsec processes are running in Cisco IOS XR Software by default.
See the Details section in the bug ID(s) at the top of this advisory for the most complete and current information.
Determine the Status of the IPsec Processes
Administrators can determine whether IPsec processes are running on a device by using the show processes | include ipsec command in the device CLI. The following example shows the output of this command on a device on which both IPsec processes are running:
RP/0/RP0/CPU0:ios#show processes | include ipsec
Thu Feb 27 13:42:05.618 UTC
222 5460 0K 20 Sleeping ipsec_mp 0
222 6055 0K 20 Sleeping ipsec_mp 0
222 6247 0K 20 Sleeping ipsec_mp 0
222 6258 0K 20 Sleeping ipsec_mp 0
222 6502 0K 20 Sleeping ipsec_mp 0
312 5461 0K 20 Sleeping ipsec_pp 0
312 6044 0K 20 Sleeping ipsec_pp 0
312 6220 0K 20 Sleeping ipsec_pp 0
312 6375 0K 20 Sleeping ipsec_pp 0
312 6824 0K 20 Sleeping ipsec_pp 0If the command does not return any output, the IPsec processes are not running and the device is not vulnerable.
Products Confirmed Not Vulnerable
Only products listed in the Vulnerable Products section of this advisory are known to be affected by this vulnerability.
Cisco has confirmed that this vulnerability does not affect Cisco IOS or IOS XE Software.
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When this vulnerability has been exploited successfully, syslog logging will show messages like the following with a depletion level of 100 percent or close to 100 percent:
%PKT_INFRA-PAKWATCH-2-DEPLETION_CATASTROPHIC : Depletion level 100 percent for resource PAK FSV
%PKT_INFRA-PAKWATCH-6-USER_INFO : Top 5 users of PAK FSV:
%PKT_INFRA-PAKWATCH-6-INFO_HEAD : PROCESS NAME PID COUNT
%PKT_INFRA-PAKWATCH-6-INFO_BODY : pkg/bin/ipsec_pp 540912 9984
%PKT_INFRA-PAKWATCH-6-INFO_BODY : pkg/bin/udp 540892 16
%PKT_INFRA-PAKWATCH-6-USER_INFO2 : Only 2 users found using PAK FSV.Manual intervention is required to recover from this failure condition by restarting the IPsec processes as shown in the following example:
RP/0/RP0/CPU0:ios#process restart ipsec_mp
Fri Feb 21 14:48:58.121 UTC
RP/0/RP0/CPU0:ios#process restart ipsec_pp
Fri Feb 21 14:49:00.973 UTC
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To prevent exploitability of this vulnerability, administrators can apply access-control lists (ACLs) that deny ICMP unreachable packets to an affected device.
Customers that do not use any IPsec features can also disable the IPsec processes as shown in the following example:
RP/0/RP0/CPU0:ios#process shutdown ipsec_mp
Fri Feb 21 14:56:03.870 UTC
Process Shutdown of a process could leave the System in an Inconsistent State. Proceed? [confirm]
RP/0/RP0/CPU0:ios#process shutdown ipsec_pp
Fri Feb 21 14:56:09.124 UTC
Process Shutdown of a process could leave the System in an Inconsistent State. Proceed? [confirm]
RP/0/RP0/CPU0:ios#Note: Shutting down the IPsec processes is not persistent across reloads and would need to be re-applied after every system reload.
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When considering software upgrades, customers are advised to regularly consult the advisories for Cisco products, which are available from the Cisco Security Advisories and Alerts page, to determine exposure and a complete upgrade solution.
In all cases, customers should ensure that the devices to be upgraded contain sufficient memory and confirm that current hardware and software configurations will continue to be supported properly by the new release. If the information is not clear, customers are advised to contact the Cisco Technical Assistance Center (TAC) or their contracted maintenance providers.
Fixed Releases
At the time of publication, Cisco IOS XR Software releases 6.4.3 (end of 2020), 6.6.3, 7.0.2, and 7.1.1 and later contained the fix for this vulnerability. Software maintenance upgrades (SMUs) that fix this vulnerability were available for Cisco IOS XR Software releases 6.4.2 and 6.5.3 for the ASR9K-PX platform.
See the Details section in the bug ID(s) at the top of this advisory for the most complete and current information.
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The Cisco Product Security Incident Response Team (PSIRT) is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory.
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This vulnerability was found during the resolution of a Cisco TAC support case.
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To learn about Cisco security vulnerability disclosure policies and publications, see the Security Vulnerability Policy. This document also contains instructions for obtaining fixed software and receiving security vulnerability information from Cisco.
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Show LessVersion Description Section Status Date 1.0 Initial public release. — Final 2020-March-04
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