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AUSCERT External Security Bulletin Redistribution
ESB-2020.0613
Multiple Cisco UCS-Based Products UEFI Secure Boot Bypass Vulnerability
21 February 2020
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AusCERT Security Bulletin Summary
---------------------------------
Product: Cisco UCS C-Series Rack Servers
Publisher: Cisco Systems
Operating System: Network Appliance
Impact/Access: Reduced Security -- Console/Physical
Resolution: Patch/Upgrade
CVE Names: CVE-2019-1736
Reference: ESB-2019.4514
ESB-2019.4018
ESB-2019.3788
Original Bulletin:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20200219-ucs-boot-bypass
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Multiple Cisco UCS-Based Products UEFI Secure Boot Bypass Vulnerability
Priority: High
Advisory ID: cisco-sa-20200219-ucs-boot-bypass
First Published: 2020 February 19 16:00 GMT
Version 1.0: Final
Workarounds: No workarounds availableCisco Bug IDs: CSCvn09490CSCvq27796CSCvq27803
CVE-2019-1736
CWE-347
CVSS Score:
6.2 AV:P/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H/E:X/RL:X/RC:X
Summary
o A vulnerability in the firmware of the Cisco UCS C-Series Rack Servers
could allow an authenticated, physical attacker to bypass Unified
Extensible Firmware Interface (UEFI) Secure Boot validation checks and load
a compromised software image on an affected device.
The vulnerability is due to improper validation of the server firmware
upgrade images. An attacker could exploit this vulnerability by installing
a server firmware version that would allow the attacker to disable UEFI
Secure Boot. A successful exploit could allow the attacker to bypass the
signature validation checks that are done by UEFI Secure Boot technology
and load a compromised software image on the affected device. A compromised
software image is any software image that has not been digitally signed by
Cisco.
There are no workarounds that address this vulnerability. Cisco has
released firmware updates that address this vulnerability.
This advisory is available at the following link:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/
cisco-sa-20200219-ucs-boot-bypass
Affected Products
o Vulnerable Products
This vulnerability affects the following Cisco products if they are running
a vulnerable BIOS version and a vulnerable Cisco Integrated Management
Controller (IMC) firmware release:
Firepower Management Center (FMC) 1000
Firepower Management Center (FMC) 2500
Firepower Management Center (FMC) 4500
Secure Network Server 3500 Series Appliances
Secure Network Server 3600 Series Appliances
Threat Grid 5504 Appliance
UEFI Secure Boot is enabled only in a small subset of Cisco UCS-based
appliances. For all the other appliances, the feature is not used, so the
vulnerability does not apply.
For information about which BIOS versions and 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 this vulnerability.
Details
o UEFI Secure Boot was created to enhance security in the pre-boot
environment. The core issue is ensuring that a system boots without
introducing compromised code.
Ensuring that boot code is executed without modification requires the use
of a digital signature that is provided by a trusted code creator and
embedded in every executable code section. Using public/private key pairs,
the code creator "signs" their code with a private key, which can be
checked against a public key in a pre-stored signature before it is
executed.
Because of the UEFI Secure Boot feature, the software images for the
affected products are all signed by the Cisco development teams to ensure
that they have not been tampered with.
For more details on the UEFI Secure Boot feature, see the Secure Boot in
Modern Computer Security Solutions document.
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 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.
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
Customers are advised to upgrade their appliances as indicated in the
Remediation column of the following table:
Cisco First First Fixed Remediation
Hardware Fixed Cisco IMC
Platform BIOS Firmware
Version Release
FMC 1000,
2500, and 4.0.1f.0 4.0.2h Apply Hotfix CJ .
4500
Secure Apply the following patches:
Network
Server 4.0.2d 4.0.2h o SNS-35xx-BIOS-4-0-2d-0_ISE.cap
3500 o upd-pkg-SNS-35xx-cimc.full.4.0.2h.bin
Secure Apply the following patches:
Network
Server 4.0.4i 4.0.4h o SNS-36xx-BIOS-4-0-4i-0_ISE.cap
3600 o upd-pkg-SNS-36xx-cimc.full.4.0.4h.bin
Threat 4.0.2d 4.0.2h Upgrade to Release 2.8.
Grid 5504
Determine the BIOS Version and Cisco IMC Firmware Release
Cisco FMC 1000, 2500, and 4500
To determine the current BIOS version on a Cisco FMC, run the command sudo
dmidecode -t bios -q from the Linux shell (expert mode). It is not possible
to see the installed Cisco IMC firmware release, but the firmware will be
upgraded as part of Hotfix CJ along with the BIOS firmware.
Cisco Secure Network Server
The current BIOS version and Cisco IMC releases are listed in the Admin >
Firmware Management section of the web-based management interface. The
Cisco IMC firmware release is listed as BMC .
Cisco Threat Grid
It is not possible to see the current BIOS version. Instead, the Cisco
Threat Grid software release needs to be verified because the Cisco IMC
firmware will be upgraded as part of Cisco Threat Grid software release
2.8. The current build number is listed in the Operations > Update
Appliance section of the web-based management interface.
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 by Emre Demirors of Cisco 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-20200219-ucs-boot-bypass
Revision History
o +---------+-------------------------+---------+--------+------------------+
| Version | Description | Section | Status | Date |
+---------+-------------------------+---------+--------+------------------+
| 1.0 | Initial public release. | - | Final | 2020-February-19 |
+---------+-------------------------+---------+--------+------------------+
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