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ZMCIRT Vulnerability Bulletin
ZMC-2021.12.9.0800
UPDATE Small Business 220 Series Smart Switches: Multiple vulnerabilities
9th December 2021
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Product: Small Business 220 Series Smart Switches
Publisher: Cisco Systems
Operating System: Cisco
Impact/Access: Execute Arbitrary Code/Commands -- Remote/Unauthenticated
Denial of Service -- Remote/Unauthenticated
Reduced Security -- Remote/Unauthenticated
Resolution: Patch/Upgrade
CVE Names: CVE-2021-34780 CVE-2021-34779 CVE-2021-34778
CVE-2021-34777 CVE-2021-34776 CVE-2021-34775
Original Bulletin:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sb220-lldp-multivuls-mVRUtQ8T
Revision History: December 7 2021: Updated vulnerable and fixed release information.
October 7 2021: Initial Release
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Cisco Small Business 220 Series Smart Switches Link Layer Discovery Protocol
Vulnerabilities
Priority: High
Advisory ID: cisco-sa-sb220-lldp-multivuls-mVRUtQ8T
First Published: 2021 October 6 16:00 GMT
Last Updated: 2021 December 6 15:31 GMT
Version 1.1: Final
Workarounds: No workarounds available
Cisco Bug IDs: CSCvz29108 CSCvz29116 CSCvz29120 CSCvz29121 CSCvz29126
CSCvz29134
CVE Names: CVE-2021-34775 CVE-2021-34776 CVE-2021-34777 CVE-2021-34778
CVE-2021-34779 CVE-2021-34780
CWEs: CWE-120 CWE-125
Summary
o Multiple vulnerabilities exist in the Link Layer Discovery Protocol (LLDP)
implementation for Cisco Small Business 220 Series Smart Switches. An
unauthenticated, adjacent attacker could perform the following:
Execute code on the affected device or cause it to reload unexpectedly
Cause LLDP database corruption on the affected device
For more information about these vulnerabilities, see the Details section
of this advisory.
Note: LLDP is a Layer 2 protocol. To exploit these vulnerabilities, an
attacker must be in the same broadcast domain as the affected device (Layer
2 adjacent).
Cisco has released firmware updates that address these vulnerabilities.
There are no workarounds that address these vulnerabilities.
This advisory is available at the following link:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sb220-lldp-multivuls-mVRUtQ8T
Affected Products
o Vulnerable Products
These vulnerabilities affect Cisco Small Business 220 Series Smart Switches
if they are running a vulnerable firmware release and have the LLDP feature
enabled.
Note: LLDP is enabled by default on all LAN ports on Cisco Small Business
220 Series Smart Switches.
For information about which Cisco firmware 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 these vulnerabilities.
Details
o The vulnerabilities are not dependent on one another. Exploitation of one
of the vulnerabilities is not required to exploit another vulnerability. In
addition, a software release that is affected by one of the vulnerabilities
may not be affected by the other vulnerabilities.
Details about the vulnerabilities are as follows:
CVE-2021-34779, CVE-2021-34780:
Cisco Small Business 220 Series Smart Switches Link Layer Discovery
Protocol Denial of Service Vulnerabilities
Multiple vulnerabilities in the Link Layer Discovery Protocol of Cisco
Small Business 220 Series Smart Switches could allow an unauthenticated,
adjacent attacker to cause an affected device to reload unexpectedly.
These vulnerabilities are due to insufficient boundary checks when
processing LLDP messages. An attacker could exploit these vulnerabilities
by sending a malicious LLDP packet to the targeted device. A successful
exploit could allow the attacker to execute code on the affected device or
cause it to reload unexpectedly, resulting in a denial of service
condition.
Cisco has released firmware updates that address these vulnerabilities.
There are no workarounds that address these vulnerabilities.
Bug ID(s): CSCvz29121 , CSCvz29126
CVE ID: CVE-2021-34779, CVE-2021-34780
Security Impact Rating (SIR): High
CVSS Base Score: 8.8
CVSS Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVE-2021-34775, CVE-2021-34776, CVE-2021-34777, CVE-2021-34778:
Cisco Small Business 220 Series Smart Switches Link Layer Discovery
Protocol Database Corruption Vulnerabilities
Multiple vulnerabilities in the Link Layer Discovery Protocol of Cisco
Small Business 220 Series Smart Switches could allow an unauthenticated,
adjacent attacker to cause LLDP memory corruption on an affected device.
These vulnerabilities are due to missing length validation checks when
processing LLDP messages. An attacker could exploit these vulnerabilities
by sending a malicious LLDP packet to the targeted device. A successful
exploit could allow the attacker to cause an out-of-bounds read of the
valid LLDP packet data, which could allow the attacker to cause corruption
in the internal LLDP database of the affected device.
Cisco has released firmware updates that address these vulnerabilities.
There are no workarounds that address these vulnerabilities.
Bug ID(s): CSCvz29108 , CSCvz29116 , CSCvz29120 , CSCvz29134
CVE ID: CVE-2021-34775, CVE-2021-34776, CVE-2021-34777, CVE-2021-34778
Security Impact Rating (SIR): Medium
CVSS Base Score: 4.3
CVSS Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Workarounds
o There are no workarounds that address these vulnerabilities. However,
administrators may disable the affected feature.
To disable LLDP on the LAN interface of a device, do the following:
1. Open the web-based management interface and choose Administration >
Discovery LLDP > Properties .
2. Uncheck the LLDP Status check box.
While this mitigation has been deployed and was proven successful in a test
environment, customers should determine the applicability and effectiveness
in their own environment and under their own use conditions. Customers
should be aware that any workaround or mitigation that is implemented may
negatively impact the functionality or performance of their network based
on intrinsic customer deployment scenarios and limitations. Customers
should not deploy any workarounds or mitigations before first evaluating
the applicability to their own environment and any impact to such
environment.
Fixed Software
o Cisco has released free software updates that address the vulnerabilities
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
In the following table(s), the left column lists Cisco firmware releases.
The right column indicates whether a release is affected by the
vulnerabilities described in this advisory and the first release that
includes the fix for these vulnerabilities. Customers are advised to
upgrade to an appropriate fixed firmware release as indicated in this
section.
Cisco Firmware Release First Fixed Release
1.2.1.2 and earlier 1.2.1.5
To download the firmware from the Software Center on Cisco.com, click
Browse all and navigate to Switches > LAN Switches - Small Business > 220
Series Smart Switches .
The Cisco Product Security Incident Response Team (PSIRT) validates only
the affected and fixed release information that is documented in this
advisory.
Exploitation and Public Announcements
o The Cisco PSIRT is not aware of any public announcements or malicious use
of the vulnerabilities that are described in this advisory.
Source
o Cisco would like to thank Qian Chen of the Codesafe Team of Legendsec at
Qi'anxin Group for reporting these vulnerabilities.
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-sb220-lldp-multivuls-mVRUtQ8T
Revision History
o +---------+-----------------------------+----------+--------+-------------+
| Version | Description | Section | Status | Date |
+---------+-----------------------------+----------+--------+-------------+
| 1.1 | Updated vulnerable and | Fixed | Final | 2021-DEC-06 |
| | fixed release information. | Releases | | |
+---------+-----------------------------+----------+--------+-------------+
| 1.0 | Initial public release. | - | Final | 2021-OCT-06 |
+---------+-----------------------------+----------+--------+-------------+
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ZMCIRT has made every effort to ensure that the information contained
in this document is accurate. However, the decision to use the information
described is the responsibility of each user or organisation. The decision to
follow or act on information or advice contained in this security bulletin is
the responsibility of each user or organisation, and should be considered in
accordance with your organisation's site policies and procedures. ZMCERT
takes no responsibility for consequences which may arise from following or
acting on information or advice contained in this security bulletin.
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