CVE-2021-44850 : What You Need to Know

On Xilinx Zynq-7000 SoC devices, physical modification of an SD boot image allows for a buffer overflow attack in the ROM. This vulnerability arises due to an unencrypted and unauthenticated boot image header on the Zynq-7000, enabling attackers to modify register initialization values and cause a buffer overflow.

Understanding CVE-2021-44850

What is CVE-2021-44850?

The CVE-2021-44850 vulnerability allows attackers to manipulate the boot image header on Xilinx Zynq-7000 SoC devices, leading to a buffer overflow attack in the ROM. By modifying specific registers, such as those controlling the SD card's transfer type and size, an attacker can exploit this vulnerability.

The Impact of CVE-2021-44850

This vulnerability poses a severe security risk as it enables unauthorized parties to bypass secure boot mechanisms and gain control over system register values, potentially leading to unauthorized access and malicious activities.

Technical Details of CVE-2021-44850

Vulnerability Description

The unencrypted and unauthenticated boot image header on Xilinx Zynq-7000 SoC devices allows attackers to manipulate register initialization values, leading to a buffer overflow attack in the ROM.

Affected Systems and Versions

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Exploitation Mechanism

Attackers can modify the boot header stored on an SD card to make a secure image appear unencrypted.
By altering critical registers like those controlling SD card transfer type and size, a buffer overflow in the ROM can be triggered.

Mitigation and Prevention

Immediate Steps to Take

Disable boot devices and interfaces not necessary for system operation to reduce attack surface.
Implement secure boot mechanisms and regularly update firmware to patch security vulnerabilities.

Long-Term Security Practices

Conduct regular security assessments and penetration testing to identify and address vulnerabilities proactively.
Train personnel on secure coding practices and adherence to secure boot procedures.

Patching and Updates

Apply security patches and updates released by Xilinx to fix the vulnerability and enhance system security.