CVE-2024-34455 identifies a security vulnerability in Buildroot, an open-source tool that simplifies the process of building embedded Linux systems. The issue arises because the /dev/shm directory, which is used for POSIX shared memory and typically requires the sticky bit to prevent unauthorized deletion or renaming of files by non-owners, lacks this sticky bit in versions prior to commit 0b2967e. The sticky bit is a permission setting that restricts file deletion within a directory to the file owner, directory owner, or root. Without it, any user with access to /dev/shm can delete or rename files created by other users, potentially leading to confidentiality violations. The vulnerability has a CVSS 3.1 base score of 7.5, reflecting its network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:N), no user interaction (UI:N), unchanged scope (S:U), high confidentiality impact (C:H), and no impact on integrity or availability (I:N, A:N). This means an attacker can exploit this remotely without authentication or user interaction to access or manipulate sensitive data stored in shared memory. The vulnerability is classified under CWE-276 (Incorrect Default Permissions). The fix was introduced in Buildroot version 2024.02.2, which correctly sets the sticky bit on /dev/shm. No public exploits or active exploitation have been reported yet, but the vulnerability poses a significant risk to embedded devices and systems built using affected Buildroot versions.

The primary impact of CVE-2024-34455 is the potential unauthorized deletion or renaming of files in the /dev/shm directory, which can lead to confidentiality breaches. Since /dev/shm is used for shared memory, sensitive information or inter-process communication data could be exposed or disrupted. Although integrity and availability are not directly impacted, the loss or manipulation of shared memory files can cause application errors or data leakage. The vulnerability is exploitable remotely without authentication or user interaction, increasing the risk of widespread exploitation if attackers gain network access to affected devices. Embedded systems, IoT devices, and network appliances built with vulnerable Buildroot versions are at risk, potentially affecting critical infrastructure, industrial control systems, and consumer electronics. The lack of the sticky bit can facilitate privilege escalation or lateral movement within compromised environments. Organizations using Buildroot-based firmware should consider this vulnerability a high risk due to the ease of exploitation and the sensitive nature of shared memory data.

To mitigate CVE-2024-34455, organizations should immediately upgrade to Buildroot version 2024.02.2 or later, which includes the fix that properly sets the sticky bit on the /dev/shm directory. For existing deployments where upgrading firmware is not immediately feasible, administrators should manually verify and correct the permissions of /dev/shm by setting the sticky bit (chmod 1777 /dev/shm) during system initialization. Implement network segmentation and access controls to limit exposure of embedded devices and reduce the attack surface. Monitor systems for unusual file deletions or renaming activities within /dev/shm. Employ runtime integrity monitoring tools to detect unauthorized permission changes. Additionally, review and harden other default permissions in the embedded environment to prevent similar misconfigurations. Regularly audit embedded device firmware and configurations for compliance with security best practices. Finally, maintain an inventory of devices using Buildroot to prioritize patching and mitigation efforts.