CVE-2022-30790: Denx U-Boot Buffer Overflow Vulnerability

CVE-2022-30790 Overview

Das U-Boot 2022.01 contains a buffer overflow vulnerability (CWE-787: Out-of-bounds Write) that could allow an attacker with local access to potentially execute arbitrary code or cause system instability. This vulnerability is distinct from CVE-2022-30552, which addresses a separate security issue in the same bootloader.

U-Boot (Universal Bootloader) is a widely used open-source bootloader for embedded systems, including ARM, MIPS, and x86 architectures. It is commonly deployed in IoT devices, network equipment, consumer electronics, and industrial systems. A vulnerability in U-Boot can have significant implications for device security, as the bootloader operates at a privileged level before the operating system loads.

Critical Impact

Buffer overflow in Das U-Boot 2022.01 could allow local attackers to compromise system integrity through out-of-bounds memory writes, potentially leading to code execution at the bootloader level.

Affected Products

• Das U-Boot version 2022.01
• Embedded devices and systems utilizing DENX U-Boot 2022.01
• IoT devices, routers, and industrial systems running vulnerable U-Boot versions

Discovery Timeline

• 2022-06-08 - CVE-2022-30790 published to NVD
• 2025-11-03 - Last updated in NVD database

Technical Details for CVE-2022-30790

Vulnerability Analysis

The vulnerability exists in Das U-Boot 2022.01 and is classified as an out-of-bounds write (CWE-787). This type of vulnerability occurs when software writes data past the end or before the beginning of the intended buffer. In the context of a bootloader like U-Boot, such vulnerabilities are particularly dangerous because they operate before the operating system's security mechanisms are active.

Buffer overflow vulnerabilities in bootloaders can be exploited to:

• Overwrite adjacent memory regions containing critical data structures
• Corrupt the execution flow to redirect to attacker-controlled code
• Bypass secure boot mechanisms if present
• Gain persistent access at the firmware level

The local attack vector indicates that an attacker would need either physical access to the device or the ability to execute code on the target system to exploit this vulnerability.

Root Cause

The root cause is improper bounds checking when handling data in U-Boot 2022.01. The software fails to properly validate the size of input data before writing it to a fixed-size buffer, allowing data to overflow beyond the allocated memory region. This out-of-bounds write condition can corrupt adjacent memory structures and potentially allow an attacker to control program execution.

Attack Vector

The vulnerability requires local access to exploit, meaning an attacker would need:

• Physical access to the device during the boot process
• Access through a debug interface (UART, JTAG, etc.)
• The ability to influence bootloader execution through other means such as compromised storage media or network boot scenarios

The attack does not require user interaction and can be performed with low privileges, though the attacker must have local access to the target system. Successful exploitation could result in complete compromise of confidentiality, integrity, and availability of the affected system.

Due to the sensitive nature of this vulnerability and in accordance with responsible disclosure practices, specific exploitation code is not provided. For detailed technical analysis, refer to the NCC Group Advisory CVE-2022-30790 which contains comprehensive technical details about the buffer overflow condition.

Detection Methods for CVE-2022-30790

Indicators of Compromise

• Unexpected device behavior during boot sequences
• Modified bootloader configuration or environment variables
• Unusual memory corruption errors in boot logs
• Firmware integrity check failures if secure boot is implemented

Detection Strategies

• Verify U-Boot version using the version command at the bootloader prompt and compare against 2022.01
• Implement firmware integrity monitoring to detect unauthorized modifications to the bootloader
• Monitor serial console output during boot for anomalous behavior or error messages
• Use hardware-based attestation where available to verify bootloader integrity

Monitoring Recommendations

• Enable and review boot logs for signs of exploitation attempts or memory corruption
• Implement continuous monitoring of device firmware versions across your fleet
• Deploy network-based anomaly detection for devices that may exhibit changed behavior post-exploitation
• Maintain an accurate inventory of all embedded devices and their bootloader versions

How to Mitigate CVE-2022-30790

Immediate Actions Required

• Identify all devices in your environment running Das U-Boot 2022.01
• Prioritize patching based on device criticality and exposure level
• Restrict physical access to affected devices where possible
• Disable unnecessary debug interfaces (UART, JTAG) on production devices

Patch Information

DENX has addressed this vulnerability in subsequent U-Boot releases. Organizations should update to the latest stable version of U-Boot that contains the security fix. The official U-Boot repository can be accessed via the GitHub U-Boot Tags page to identify patched versions.

For Debian-based systems, refer to the Debian LTS Announcement for package update information.

Workarounds

• Restrict physical access to devices running vulnerable U-Boot versions
• Disable or secure debug interfaces (UART, JTAG) to prevent unauthorized access to the bootloader
• Implement network segmentation to isolate affected embedded devices
• Enable secure boot where supported to prevent execution of modified bootloader code
• Monitor for firmware tampering using out-of-band integrity verification

# Verify U-Boot version (at bootloader prompt)
version

# Disable autoboot to prevent automated exploitation
setenv bootdelay -1
saveenv

# Restrict network boot if not required
setenv ipaddr
setenv serverip
saveenv