Vulnerability Note VU#507496
GIGABYTE BRIX UEFI firmware fails to implement write protection and is not cryptographically signed
Original Release date: 31 Mar 2017 | Last revised: 31 Mar 2017

Overview
GIGABYTE BRIX UEFI firmware for the GB-BSi7H-6500 and GB-BXi7-5775 platforms, versions vF6 and vF2 respectively, fails to properly set the BIOSWE, BLE, SMM_BWP, and PRx bits to enforce write protection. It also is not cryptographically signed. These issues may permit an attacker to write arbitrary code to the platform firmware, potentially allowing for persistent firmware level rootkits or the creation of a permanent denial of service condition in the platform.

Description
CWE-693: Protection Mechanism Failure – CVE-2017-3197
GIGABYTE UEFI firmware for the GB-BSi7H-6500 and GB-BXi7-5775 platforms fails to properly set the BIOSWE, BLE, SMM_BWP, and PRx bits. As a result, the BIOS is not protected from arbitrary write access and may permit modifications to the SPI flash.

CWE-345: Insufficient Verification of Data Authenticity – CVE-2017-3198

GIGABYTE UEFI firmware for the GB-BSi7H-6500 and GB-BXi7-5775 platforms is not cryptographically signed and is served over HTTP from the vendor’s support pages without a checksum. An attacker in the position to do so may introduce arbitrary modifications to the firmware that the system has no means to detect.

Note that the affected GIGABYTE firmware is a vulnerable implementation of an AMI reference design that does not, by default, appear to be affected by these issues. For more information about these findings, refer to the Cylance advisories, CLVA-2017-01-001 and CLVA-2017-01-002.

Impact
A local, authenticated attacker may be able to execute arbitrary code with the privileges of system firmware, potentially allowing for persistent firmware level rootkits or the creation of a permanent denial of service condition in the platform.

Solution
The vendor has indicated that firmware version F7 for the GB-BSi7H-6500 will be released in April to address these issues. Users should monitor the product page or contact the vendor for update availability.

The vendor has indicated that the GB-BXi7-5775 is end of life and will not receive new firmware.

The CERT/CC is currently unaware of a practical solution for these problems.

Vendor Information (Learn More)

VendorStatusDate NotifiedDate UpdatedGIGABYTEAffected24 Jan 201722 Mar 2017If you are a vendor and your product is affected, let
us know.

CVSS Metrics (Learn More)

Group
Score
Vector

Base
6.0
AV:L/AC:H/Au:S/C:C/I:C/A:C

Temporal
5.1
E:POC/RL:ND/RC:UR

Environmental
7.1
CDP:MH/TD:ND/CR:ND/IR:H/AR:ND

References

https://cwe.mitre.org/data/definitions/693.html
https://cwe.mitre.org/data/definitions/353.html
http://www.gigabyte.us/Mini-PcBarebone/GB-BSi7H-6500-rev-10
http://www.gigabyte.us/Mini-PcBarebone/GB-BXi7-5775-rev-10
https://github.com/CylanceVulnResearch/disclosures/blob/master/CLVA-2017-01-001.md
https://github.com/CylanceVulnResearch/disclosures/blob/master/CLVA-2017-01-002.md

Credit

Thanks to Alex Matrosov of Cylance for reporting these vulnerabilities.
This document was written by Joel Land.

Other Information

CVE IDs:
CVE-2017-3197
CVE-2017-3198

Date Public:
31 Mar 2017

Date First Published:
31 Mar 2017

Date Last Updated:
31 Mar 2017

Document Revision:
31

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