Vulnerabilities > CVE-2020-25860 - Time-of-check Time-of-use (TOCTOU) Race Condition vulnerability in Pengutronix Rauc
Attack vector
NETWORK Attack complexity
HIGH Privileges required
SINGLE Confidentiality impact
COMPLETE Integrity impact
COMPLETE Availability impact
COMPLETE Summary
The install.c module in the Pengutronix RAUC update client prior to version 1.5 has a Time-of-Check Time-of-Use vulnerability, where signature verification on an update file takes place before the file is reopened for installation. An attacker who can modify the update file just before it is reopened can install arbitrary code on the device.
Vulnerable Configurations
| Part | Description | Count |
|---|---|---|
| Application | 11 |
Common Weakness Enumeration (CWE)
Common Attack Pattern Enumeration and Classification (CAPEC)
- Leveraging Race Conditions via Symbolic Links This attack leverages the use of symbolic links (Symlinks) in order to write to sensitive files. An attacker can create a Symlink link to a target file not otherwise accessible to her. When the privileged program tries to create a temporary file with the same name as the Symlink link, it will actually write to the target file pointed to by the attackers' Symlink link. If the attacker can insert malicious content in the temporary file she will be writing to the sensitive file by using the Symlink. The race occurs because the system checks if the temporary file exists, then creates the file. The attacker would typically create the Symlink during the interval between the check and the creation of the temporary file.
- Leveraging Time-of-Check and Time-of-Use (TOCTOU) Race Conditions This attack targets a race condition occurring between the time of check (state) for a resource and the time of use of a resource. The typical example is the file access. The attacker can leverage a file access race condition by "running the race", meaning that he would modify the resource between the first time the target program accesses the file and the time the target program uses the file. During that period of time, the attacker could do something such as replace the file and cause an escalation of privilege.