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AUSCERT External Security Bulletin Redistribution
ESB-2020.1942
Cisco ASR 920 Series Aggregation Services Router Model
12SZ-IM SNMP Denial of Service Vulnerability
4 June 2020
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AusCERT Security Bulletin Summary
---------------------------------
Product: Cisco ASR 920 Series Aggregation Services Router
Publisher: Cisco Systems
Operating System: Cisco
Impact/Access: Denial of Service -- Existing Account
Resolution: Patch/Upgrade
CVE Names: CVE-2020-3232
Original Bulletin:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asr920-ABjcLmef
- --------------------------BEGIN INCLUDED TEXT--------------------
Cisco ASR 920 Series Aggregation Services Router Model 12SZ-IM SNMP Denial of
Service Vulnerability
Priority: Medium
Advisory ID: cisco-sa-asr920-ABjcLmef
First Published: 2020 June 3 16:00 GMT
Version 1.0: Final
Workarounds: Yes
Cisco Bug IDs: CSCvi42821
CVE-2020-3232
CWE-19
CVSS Score:
6.3 AV:N/AC:H/PR:L/UI:N/S:C/C:N/I:N/A:H/E:X/RL:X/RC:X
Summary
o
A vulnerability in the Simple Network Management Protocol (SNMP)
implementation in Cisco ASR 920 Series Aggregation Services Router model
ASR920-12SZ-IM could allow an authenticated, remote attacker to cause the
device to reload.
The vulnerability is due to incorrect handling of data that is returned for
Cisco Discovery Protocol queries to SNMP. An attacker could exploit this
vulnerability by sending a request for Cisco Discovery Protocol information
by using SNMP. An exploit could allow the attacker to cause the affected
device to reload, resulting in a denial of service (DoS) condition.
Cisco has released software updates that address this vulnerability. There
are workarounds that address this vulnerability.
This advisory is available at the following link:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/
cisco-sa-asr920-ABjcLmef
Affected Products
o Vulnerable Products
This vulnerability affects the Cisco ASR 920 Series Aggregation Services
Router model ASR920-12SZ-IM if it is configured with both SNMP (either
Version 2c or 3) and Cisco Discovery Protocol.
For information about which Cisco IOS XE Software releases for Cisco ASR
model ASR920-12SZ-IM 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.
No other models of the Cisco ASR 920 Series Aggregation Services Routers
are affected by this vulnerability.
Details
o This advisory has been scored as having a Medium Security Impact Rating
(SIR) rather than a High SIR because the exploit does not consistently
cause the device to be reloaded.
Workarounds
o Excluding the MIB CISCO-CDP-MIB is a workaround for this vulnerability. The
following example shows exclusion of CISCO-CDP-MIB .
1. Create the cutdown view:
snmp-server view cutdown iso included
snmp-server view cutdown 1.3.6.1.4.1.9.9.23 excluded
2. Apply the cutdown view to the SNMPv2 community string or SNMPv3 group:
#SNMPv2:
snmp-server community Examplev2 view cutdown
#SNMPv3:
SNMP-Server group Examplev3Group v3 priv Read cutdown Write cutdown
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 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.
Cisco IOS and IOS XE Software
To help customers determine their exposure to vulnerabilities in Cisco IOS
and IOS XE Software, Cisco provides the Cisco Software Checker to identify
any Cisco Security Advisories that impact a specific software release and
the earliest release that fixes the vulnerabilities described in each
advisory ("First Fixed"). If applicable, the tool also returns the earliest
release that fixes all the vulnerabilities described in all the advisories
identified ("Combined First Fixed").
Customers can use the Cisco Software Checker to search advisories in the
following ways:
Choose the software and one or more releases
Upload a .txt file that includes a list of specific releases
Enter the output of the show version command
After initiating a search, customers can customize the search to include
all Cisco Security Advisories, a specific advisory, or all advisories in
the most recent bundled publication.
Customers can also use the following form to determine whether a release is
affected by any Cisco Security Advisory by entering a Cisco IOS or IOS XE
Software release-for example, 15.1(4)M2 or 3.13.8S :
[ ] [Check]
By default, the Cisco Software Checker includes results only for
vulnerabilities that have a Critical or High Security Impact Rating (SIR).
To include results for Medium SIR vulnerabilities, customers can use the
Cisco Software Checker on Cisco.com and check the Medium check box in the
drop-down list under Impact Rating when customizing a search.
For a mapping of Cisco IOS XE Software releases to Cisco IOS Software
releases, refer to the Cisco IOS XE 2 Release Notes , Cisco IOS XE 3S
Release Notes , or Cisco IOS XE 3SG Release Notes , depending on the Cisco
IOS XE Software release.
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-asr920-ABjcLmef
Revision History
o +----------+---------------------------+----------+--------+--------------+
| Version | Description | Section | Status | Date |
+----------+---------------------------+----------+--------+--------------+
| 1.0 | Initial public release. | - | Final | 2020-JUN-03 |
+----------+---------------------------+----------+--------+--------------+
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