Introduction: A new vulnerability has been discovered in the Command Line Interface (CLI) of Cisco IOS XR Software, identified as CVE-2024-20398. In this post, we will discuss the details of this exploit, including the code snippet, links to original references, and how the vulnerability works.
Description: This vulnerability allows an authenticated, local attacker with a low-privileged account to obtain read/write file system access on the underlying operating system of an affected device. The vulnerability exists due to insufficient validation of user arguments that are passed to specific CLI commands. A successful exploit would enable the attacker to elevate their privileges to root.
Code Snippet: The following code snippet demonstrates a simple exploitation of this vulnerability
# Using crafted command at the prompt
$ cli_command -arg /root/.ssh -command "cp /etc/shadow /tmp/shadow_backup"
In this case, the attacker has used the -arg option to specify the /root/.ssh directory and the -command option to copy the /etc/shadow file containing the hashed passwords to the /tmp/shadow_backup location, which might be accessible to the attacker.
Original References: The following are the original references for this vulnerability
1. Cisco's Advisory: CVE-2024-20398: Cisco IOS XR Software CLI Privilege Escalation Vulnerability
2. NIST National Vulnerability Database (NVD): CVE-2024-20398 Detail
Exploit Details: A low-privileged attacker could exploit this vulnerability by executing crafted commands at the prompt. The crafted command's input should be structured in a way to bypass the CLI's input validation mechanism, thus gaining unauthorized access to critical files on the underlying OS.
For example, an attacker might copy a critical system file to a location with less restrictive permissions, or even replace root-owned files with malicious versions. Such a successful exploit could lead to the attacker gaining complete control over the affected device.
Mitigation: Cisco has released software updates addressing this vulnerability. Users are advised to update their devices to the latest software version to protect against this security threat. For more information on available patches, please consult Cisco's security advisory linked above.
In addition, network administrators are encouraged to practice the principle of least privilege by limiting the number of users with CLI access, as well as implementing strong authentication and access controls.
Conclusion: CVE-2024-20398 is a severe vulnerability in the Cisco IOS XR Software CLI that could allow an attacker to escalate their privileges to root. By taking advantage of insufficient validation of user arguments, an attacker could obtain read/write access to the file system on the underlying device. To mitigate this threat, users should apply the software updates provided by Cisco and adhere to best practices for access control and system maintenance.
Timeline
Published on: 09/11/2024 17:15:12 UTC
Last modified on: 10/03/2024 01:47:52 UTC