CVE CyberSecurity Database News

CVE-2023-52440 - Patched Linux Kernel Vulnerability in ksmbd_decode_ntlmssp_auth_blob()

Poster -

In recent years, the software security landscape has witnessed a countless number of vulnerabilities that have had a significant impact on the overall stability and security of various systems. Among the many vulnerabilities discovered, CVE-2023-52440 identifies a critical slub overflow issue in the Linux kernel. Specifically, the vulnerability exists within the ksmbd_decode_ntlmssp_auth_blob() function.

The Linux kernel is the central part of the Linux operating system and provides the core functionality, such as task scheduling, memory management, and file systems. It serves as a bridge between applications and the hardware of a computer.

In this article, we will delve into the details of the CVE-2023-52440 vulnerability, as well as its associated code snippet, original references, and exploit details.

CVE-2023-52440 Details

The vulnerability underlying CVE-2023-52440 is present in the Linux kernel (ksmbd) function called ksmbd_decode_ntlmssp_auth_blob(). If the authblob->SessionKey.Length is found to be larger than the session key size (CIFS_KEY_SIZE), a slub overflow will occur within the key exchange codes.

For context, a "slub overflow" typically refers to a memory-corruption issue in the Linux kernel's slab memory allocator. This specific vulnerability could potentially result in unauthorized access, denial of service, information disclosure, or escalation of privileges.

Here is the code snippet that demonstrates the issue

int ksmbd_decode_ntlmssp_auth_blob(struct ksmbd_authinfo *auth_info,
        char *ntlmssp_blob, unsigned int ntlmssp_blob_len)
{
    ...
    if (auth_blob->SessionKey.Length > CIFS_KEY_SIZE) {
            ksmbd_debug(SMB, "Session key length is too long: %d\n",
                        auth_blob->SessionKey.Length);
            ret = -EINVAL;
            goto out;
    }
    ...
}

In the above code snippet, the function checks if auth_blob->SessionKey.Length is greater than CIFS_KEY_SIZE. If this is the case, the function will print an error message, set the return value to EINVAL, and exit.

Exploit Details

To exploit this vulnerability, an attacker would need to transmit a carefully-crafted message that would cause the Linux kernel to overflow its slub memory allocator. This could lead to a variety of adverse consequences, such as unauthorized access to sensitive information or the corruption of kernel data structures, depending on the specific memory layout at the time of the overflow.

1. CVE-2023-52440 - Official CVE entry in the MITRE database.

2. Linux Kernel Repository - The official GitHub repository for the Linux kernel.

3. Linux Kernel Mailing List - The mailing list announcement of the patch that addresses the CVE-2023-52440 vulnerability.

Conclusion

In conclusion, the Linux kernel vulnerability CVE-2023-52440 highlights the importance of having a robust and secure kernel. The Linux kernel team has addressed this issue through their continuous efforts to improve the overall security of the Linux operating system. As always, make sure your system's kernel is up-to-date, and stay vigilant when it comes to security.

Timeline

Published on: 02/21/2024 08:15:45 UTC
Last modified on: 03/15/2024 13:44:59 UTC