Red Hat Enterprise Linux Cloud-Init Privilege Escalation Vulnerability

A vulnerability exists within the cloud-init component of Red Hat Enterprise Linux. An attacker positioned on an adjacent network can exploit this flaw to escalate their privileges to administrator level. This poses a significant risk, as successful exploitation grants the attacker full control over the affected system, potentially leading to data breaches, system compromise, and further lateral movement within the network. Defenders must prioritize patching and implement detection measures to mitigate this risk.

Attack Chain

1. Attacker gains access to a network adjacent to the target Red Hat Enterprise Linux system.
2. Attacker crafts a malicious cloud-init configuration.
3. Attacker injects the malicious cloud-init configuration into the target system (details of the injection method are unspecified).
4. The cloud-init service processes the malicious configuration.
5. Due to the vulnerability, processing the configuration triggers unintended code execution with elevated privileges.
6. Attacker leverages the elevated privileges to create a new administrator account.
7. Attacker logs in to the system using the newly created administrator account.
8. Attacker performs malicious activities, such as installing malware, exfiltrating data, or further compromising the network.

Impact

Successful exploitation of this vulnerability results in complete compromise of the targeted Red Hat Enterprise Linux system. The attacker gains full administrator privileges, allowing them to perform any action on the system. This could lead to data theft, system downtime, installation of backdoors, and further propagation of the attack to other systems on the network. The number of potential victims is dependent on the number of vulnerable Red Hat Enterprise Linux systems within an organization’s infrastructure.

Recommendation

• Apply the latest security patches for cloud-init on Red Hat Enterprise Linux systems to remediate the vulnerability.
• Monitor systems for unexpected process creation by the cloud-init service (/usr/bin/cloud-init) with the Sigma rule provided below.
• Closely monitor user account creation events for suspicious activity, especially accounts created shortly after cloud-init processes execute.