Cisco Security Advisory
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CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:X/RL:X/RC:X
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A vulnerability in the ROM Monitor (ROMMON) of Cisco IOS XE Software for Cisco Catalyst IE3200, IE3300, and IE3400 Rugged Series Switches, Cisco Catalyst IE3400 Heavy Duty Series Switches, and Cisco Embedded Services 3300 Series Switches could allow an unauthenticated, physical attacker to execute unsigned code at system boot time.
This vulnerability is due to incorrect validations of specific function arguments passed to a boot script when specific ROMMON variables are set. An attacker could exploit this vulnerability by setting malicious values for a specific ROMMON variable. A successful exploit could allow the attacker to execute unsigned code and bypass the image verification check during the secure boot process of an affected device. To exploit this vulnerability, the attacker would need to have unauthenticated, physical access to the device or obtain privileged access to the root shell on the device.
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://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxe-romvar-cmd-inj-N56fYbrw
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Vulnerable Products
This vulnerability affects the following Cisco routers if they are running a Cisco IOS XE ROMMON Software release earlier than Release 7.0:
- Catalyst IE3200 Rugged Series Switches
- Catalyst IE3300 Rugged Series Switches
- Catalyst IE3400 Rugged Series Switches
- Catalyst IE3400 Heavy Duty Series Switches
- Embedded Services 3300 Series Switches (ESS 3300)
Determine the Cisco IOS XE ROMMON Software Release
To determine which Cisco IOS XE ROMMON Software release is running on a device, log in to the device and use the show rom-monitor rp active command in the CLI. The following example shows the output of this command for a device that is running Cisco IOS XE ROMMON Software Release 7.1.1:
Switch# show rom-monitor rp active
Version 7.1.1 [RELEASE SOFTWARE]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 the following Cisco products:
- IOS Software
- IOS XR Software
- NX-OS Software
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There are no workarounds that address this vulnerability.
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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.htmlAdditionally, 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
The ROMMON software is a bootstrap program that initializes the hardware and boots Cisco IOS XE Software when a device is powered on or reloaded. The ROMMON software is bundled with the Cisco IOS XE binary, which can be downloaded from the Software Center on Cisco.com.
Customers are advised to upgrade to an appropriate fixed software release as indicated in the following table:
Affected Cisco Devices First Fixed Cisco IOS XE ROMMON Software Release First Fixed Cisco IOS XE Software Release Catalyst IE3200 Rugged Series Switches 7.0 and later 17.3.1 and later Catalyst IE3300 Rugged Series Switches 7.0 and later 17.3.1 and later Catalyst IE3400 Rugged Series Switches 7.0 and later 17.3.1 and later Catalyst IE3400 Heavy Duty Series Switches 7.0 and later 17.3.1 and later Embedded Service 3300 Series Switches 7.0 and later 17.3.1 and later ROMMON code is included as part of a Cisco IOS XE Software binary image, and it is not available as a standalone binary. Customers looking to upgrade their ROMMON to a fixed version will need to upgrade the Cisco IOS XE Software that is running on a device to Release 17.3.1 or later. On first boot, Cisco IOS XE Software will check the installed ROMMON version and upgrade it to Release 7.0 if the device is running an older version.
Note: If the device is downgraded to an older Cisco IOS XE Software release, the ROMMON will be rewritten with a previous ROMMON version, which may make the device vulnerable.
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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 internal security testing by X.B. of Cisco.
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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 2021-MAR-24
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