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AUSCERT External Security Bulletin Redistribution
ESB-2020.2684
Cisco StarOS IPv6 Denial of Service Vulnerabilities
6 August 2020
===========================================================================
AusCERT Security Bulletin Summary
---------------------------------
Product: Cisco ASR 5000 Series Aggregation Services Routers
Cisco Virtualized Packet Core-Single Instance (VPC-SI)
Publisher: Cisco Systems
Operating System: Cisco
Impact/Access: Denial of Service -- Remote/Unauthenticated
Resolution: Patch/Upgrade
CVE Names: CVE-2020-3500 CVE-2020-3324
Original Bulletin:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asr-dos-zJLJFgBf
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asr5k-ipv6-dos-ce3zhF8m
Comment: This bulletin contains two (2) Cisco Systems security advisories.
- --------------------------BEGIN INCLUDED TEXT--------------------
Cisco StarOS IPv6 Denial of Service Vulnerability
Priority: High
Advisory ID: cisco-sa-asr-dos-zJLJFgBf
First Published: 2020 August 5 16:00 GMT
Version 1.0: Final
Workarounds: No workarounds available
Cisco Bug IDs: CSCvs50343
CVE-2020-3324
CWE-20
CVSS Score:
8.6 AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H/E:X/RL:X/RC:X
Summary
o A vulnerability in the IPv6 implementation of Cisco StarOS could allow an
unauthenticated, remote attacker to cause a denial of service (DoS)
condition on an affected device.
The vulnerability is due to insufficient validation of incoming IPv6
traffic. An attacker could exploit this vulnerability by sending a crafted
IPv6 packet to an affected device. A successful exploit could allow the
attacker to cause an unexpected reload of the device, leading to a DoS
condition.
This vulnerability is specific to IPv6 traffic. IPv4 traffic is not
affected.
Cisco has released software updates that address this vulnerability. There
are no workarounds that address this vulnerability.
This advisory is available at the following link:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/
cisco-sa-asr-dos-zJLJFgBf
Affected Products
o Vulnerable Products
This vulnerability affects the following Cisco products if they are running
a vulnerable release of Cisco StarOS and have the Vector Packet Processing
(VPP) feature enabled. The VPP feature is disabled by default:
Cisco ASR 5000 Series Aggregation Services Routers
Cisco Virtualized Packet Core-Single Instance (VPC-SI)
To see if the VPP feature is enabled, an administrator can use the show
task table process vpp_main all command. If the command lists the vpp_main
process, the feature is enabled. The following is a sample output with the
VPP feature enabled:
[local]swch# show task table process vpp_main all
task parent
cpu facility inst pid pri node facility inst pid
---- ---------------------------------------------- -------------------------
1/0 vpp_main 1005729 5729 0 all - 0 0
For information about which Cisco software releases are vulnerable, see the
Fixed Software section of this advisory.
Products Confirmed Not Vulnerable
Only products listed in the Vulnerable Products section of this advisory
are known to be affected by this vulnerability.
Workarounds
o There are no workarounds that address this vulnerability.
Fixed Software
o Cisco has released free software updates that address the vulnerability
described in this advisory. Customers may only install and expect support
for software versions and feature sets for which they have purchased a
license. By installing, downloading, accessing, or otherwise using such
software upgrades, customers agree to follow the terms of the Cisco
software license: https://www.cisco.com/c/en/us/products/
end-user-license-agreement.html
Additionally, customers may only download software for which they have a
valid license, procured from Cisco directly, or through a Cisco authorized
reseller or partner. In most cases this will be a maintenance upgrade to
software that was previously purchased. Free security software updates do
not entitle customers to a new software license, additional software
feature sets, or major revision upgrades.
When considering software upgrades , customers are advised to regularly
consult the advisories for Cisco products, which are available from the
Cisco Security Advisories 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.
Customers Without Service Contracts
Customers who purchase directly from Cisco but do not hold a Cisco service
contract and customers who make purchases through third-party vendors but
are unsuccessful in obtaining fixed software through their point of sale
should obtain upgrades by contacting the Cisco TAC: https://www.cisco.com/c
/en/us/support/web/tsd-cisco-worldwide-contacts.html
Customers should have the product serial number available and be prepared
to provide the URL of this advisory as evidence of entitlement to a free
upgrade.
Fixed Releases
Cisco StarOS Major Release First Fixed Release for This Vulnerability
Earlier than 21.15 Migrate to 21.15.31.
21.15 21.15.31
21.16 21.16.4
21.16.c 21.16.c11
21.16.d Migrate to 21.16.4.
21.17 21.17.4
21.18 Not vulnerable.
21.19 Not vulnerable.
Exploitation and Public Announcements
o 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.
Source
o This vulnerability was found during internal security testing.
Cisco Security Vulnerability Policy
o 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.
URL
o https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/
cisco-sa-asr-dos-zJLJFgBf
Revision History
o +----------+---------------------------+----------+--------+--------------+
| Version | Description | Section | Status | Date |
+----------+---------------------------+----------+--------+--------------+
| 1.0 | Initial public release. | - | Final | 2020-AUG-05 |
+----------+---------------------------+----------+--------+--------------+
- --------------------------------------------------------------------------------
Cisco StarOS IPv6 Denial of Service Vulnerability
Priority: Medium
Advisory ID: cisco-sa-asr5k-ipv6-dos-ce3zhF8m
First Published: 2020 August 5 16:00 GMT
Version 1.0: Final
Workarounds: No workarounds available
Cisco Bug IDs: CSCvu23797
CVE-2020-3500
CWE-119
Summary
o A vulnerability in the IPv6 implementation of Cisco StarOS could allow an
unauthenticated, remote attacker to cause a denial of service (DoS)
condition on an affected device.
The vulnerability is due to insufficient validation of incoming IPv6
traffic. An attacker could exploit this vulnerability by sending a crafted
IPv6 packet to an affected device with the goal of reaching the vulnerable
section of the input buffer. A successful exploit could allow the attacker
to cause the device to reload, resulting in a DoS condition.
This vulnerability is specific to IPv6 traffic. IPv4 traffic is not
affected.
Cisco has released software updates that address this vulnerability. There
are no workarounds that address this vulnerability.
This advisory is available at the following link:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/
cisco-sa-asr5k-ipv6-dos-ce3zhF8m
Affected Products
o Vulnerable Products
At the time of publication, this vulnerability affected the following Cisco
products if they were running a release of Cisco StarOS earlier than
Release 21.18.3 and had the Vector Packet Processing (VPP) feature enabled:
Cisco ASR 5000 Series Aggregation Services Routers
Cisco Virtualized Packet Core-Single Instance (VPC-SI)
The VPP feature is disabled by default.
Determine the VPP Configuration
To see if the VPP feature is enabled, an administrator can use the command
show task table process vpp_main all. If the command lists the vpp_main
process, then the feature is enabled. The following example shows the
output of the show task table process vpp_main all command for a device
that has the VPP feature enabled:
[local]swch# show task table process vpp_main all
task parent
cpu facility inst pid pri node facility inst pid
---- ---------------------------------------------- -------------------------
1/0 vpp_main 1005729 5729 0 all - 0 0
Products Confirmed Not Vulnerable
Only products listed in the Vulnerable Products section of this advisory
are known to be affected by this vulnerability.
Workarounds
o There are no workarounds that address this vulnerability.
Fixed Software
o When considering software upgrades , customers are advised to regularly
consult the advisories for Cisco products, which are available from the
Cisco Security Advisories 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 StarOS releases 21.18.3 and later
contained the fix for this vulnerability.
See the Details section in the bug ID(s) at the top of this advisory for
the most complete and current information.
Exploitation and Public Announcements
o 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.
Source
o This vulnerability was found during the resolution of a Cisco TAC support
case.
Cisco Security Vulnerability Policy
o 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.
URL
o https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/
cisco-sa-asr5k-ipv6-dos-ce3zhF8m
Revision History
o +----------+---------------------------+----------+--------+--------------+
| Version | Description | Section | Status | Date |
+----------+---------------------------+----------+--------+--------------+
| 1.0 | Initial public release. | - | Final | 2020-AUG-05 |
+----------+---------------------------+----------+--------+--------------+
- --------------------------END INCLUDED TEXT--------------------
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