CVE-2022-34835
📋 TL;DR
CVE-2022-34835 is a critical stack-based buffer overflow vulnerability in Das U-Boot bootloader's 'i2c md' command. An attacker with access to the bootloader console can exploit this to execute arbitrary code, potentially gaining full control of the device before the operating system loads. This affects any system using vulnerable versions of Das U-Boot with I2C functionality enabled.
💻 Affected Systems
- Das U-Boot bootloader
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise via remote code execution, allowing persistent backdoor installation, bootkit deployment, or bricking of the device.
Likely Case
Local privilege escalation from limited console access to full system control, potentially leading to data theft, service disruption, or lateral movement in embedded networks.
If Mitigated
Limited impact if bootloader access is restricted via physical security or console authentication, though the vulnerability remains present in the firmware.
🎯 Exploit Status
Exploitation requires access to U-Boot console interface. The vulnerability is in command parsing, making exploitation straightforward once console access is obtained.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Fixed in commit 8f8c04bf1ebbd2f72f1643e7ad9617dafa6e5409 and later versions
Vendor Advisory: https://lists.denx.de/pipermail/u-boot/2022-June/486113.html
Restart Required: Yes
Instructions:
1. Update Das U-Boot source to version after commit 8f8c04bf1ebbd2f72f1643e7ad9617dafa6e5409. 2. Recompile bootloader. 3. Flash updated bootloader to device. 4. Reboot device.
🔧 Temporary Workarounds
Disable I2C command
allRemove or disable the 'i2c md' command from U-Boot build configuration
In U-Boot configuration: #undef CONFIG_CMD_I2C or remove I2C commands from config
Restrict console access
allImplement authentication or disable network/serial console access to U-Boot
Set CONFIG_AUTOBOOT_KEYED=y and configure boot delay to 0
Disable CONFIG_CMD_NET if network console not needed
🧯 If You Can't Patch
- Physically secure devices to prevent unauthorized console access
- Implement network segmentation to isolate devices with vulnerable bootloaders
🔍 How to Verify
Check if Vulnerable:
Check U-Boot version: 'version' command at U-Boot prompt. If version is 2022.07-rc5 or earlier, device is vulnerable.Check Version:
At U-Boot prompt: versionVerify Fix Applied:
Verify U-Boot version shows commit after 8f8c04bf1ebbd2f72f1643e7ad9617dafa6e5409 or test 'i2c md' command with invalid parameters.📡 Detection & Monitoring
Log Indicators:
- Unexpected reboots or boot failures
- Console logs showing buffer overflow messages
- I2C command usage from unusual sources
Network Indicators:
- Unexpected network traffic during boot phase
- TFTP or network boot requests from unauthorized sources
SIEM Query:
Not typically applicable as exploitation occurs before OS logging starts🔗 References
- https://github.com/u-boot/u-boot/commit/8f8c04bf1ebbd2f72f1643e7ad9617dafa6e5409
- https://lists.denx.de/pipermail/u-boot/2022-June/486113.html
- https://source.denx.de/u-boot/u-boot/-/commit/8f8c04bf1ebbd2f72f1643e7ad9617dafa6e5409
- https://github.com/u-boot/u-boot/commit/8f8c04bf1ebbd2f72f1643e7ad9617dafa6e5409
- https://lists.debian.org/debian-lts-announce/2025/05/msg00001.html
- https://lists.denx.de/pipermail/u-boot/2022-June/486113.html
- https://source.denx.de/u-boot/u-boot/-/commit/8f8c04bf1ebbd2f72f1643e7ad9617dafa6e5409
