RK3588s: Time-of-check Time-of-use (TOCTOU) Race Condition
CVE-2024-13942 is a high-severity time-of-check time-of-use (TOCTOU) race condition vulnerability in RK3588s from Rockchip, with a CVSS 3.1 base score of 7.6 out of 10. It can be exploited with physical access to the device by an unauthenticated attacker, without any action from a user. Affected RK3588s versions: 350B20210512V100. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.23% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of RK3588s you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on rock-chips.com for workarounds and exact fixed builds.
Affected products and versions
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- PhysicalThe attacker must physically touch the device.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- ChangedThe attack can reach beyond the vulnerable component into other systems.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H. Scored by CNA (kaspersky.com).
Official description
Secure BootROM of RK3588s SoC is vulnerable to a time-of-check to time-of-use attack in case of booting from external media (SPI NOR or NAND, EMMC or SD). The code reads the header of the next-stage loader twice. The header contains hashes of the executable modules and is signed with a private key, the public part of which is verified against the SHA256 digest blown in the OTP. The first read is only partial and contains only the hashes of the executable modules. The second is complete, including the header signature. Although the header is verified based on the fully read data, the authenticity of the executable modules is checked against the partial data from the first read. An attacker with physical access to a device containing RK3588s SoC can easily modify the next-stage loader data on-the-fly using a low-cost SD-card or SPI NOR/NAND or EMMC emulator. Even a simple ultra low-cost circuit comprising two memory chips (containing the same data but different headers - the original and the modified one) and a multiplexer can be used to carry out an attack. This can lead to arbitrary code execution with the highest privileges available (EL3). This issue affects RK3588s: RK3588s SoC BootROM (secure) 350B20210512V100 and possibly others. As remediation apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable https://www.rock-chips.com/a/en/products/RK35_Series/2022/0926/1660.html
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Time-of-check Time-of-use (TOCTOU) Race Condition
The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check.
How developers prevent this class of flaw
- The most basic advice for TOCTOU vulnerabilities is to not perform a check before the use. This does not resolve the underlying issue of the execution of a function on a resource whose state and identity cannot be assured, but it does help to limit the false sense of security given by the check.
- When the file being altered is owned by the current user and group, set the effective gid and uid to that of the current user and group when executing this statement.
- Limit the interleaving of operations on files from multiple processes.
More Time-of-check Time-of-use (TOCTOU) Race Condition vulnerabilities (CWE-367)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Advisories
Other references
Our coverage
Recent Time-of-check Time-of-use (TOCTOU) Race Condition vulnerabilities
- 7.0 High severity
- 7.7 High severity
- 7.3 High severity
- 7.8 High severity
- 8.8 High severity
- 8.3 High severity
Spotted an error? Tell us.