A critical security vulnerability in Microsoft Windows' Routing and Remote Access Service (RRAS) has been uncovered, dubbed CVE-2024-26179. This vulnerability allows potential attackers to execute malicious code remotely on the target machine. In simple language, an attacker can take control of your computer without your knowledge by exploiting this vulnerability.

In this post, we will take an in-depth look at the details of CVE-2024-26179, including code snippets, links to original references, and the steps taken to exploit this vulnerability.

Details

The CVE-2024-26179 vulnerability is associated with a flaw within the Windows RRAS. RRAS is a Microsoft service that, among other functions, enables remote users to connect securely to a local network using virtual private networking (VPN) technologies.

The vulnerability specifically lies in a protocol called Microsoft's Secure Socket Tunneling Protocol (SSTP). SSTP is a specialized protocol developed by Microsoft for use with VPNs in RRAS. This protocol's purpose is to establish a secure communication channel between a client machine and a server over the internet.

According to the original analysis by researchers, the vulnerability is caused due to improper handling of specially crafted SSTP packets sent to the RRAS server by an attacker. This could lead to a buffer overflow condition, which could result in arbitrary code execution.

Code Snippet: (simplified example of vulnerable function)

void process_sstp_packet(unsigned char* packet_data, int packet_length)
{
    unsigned char buffer[1024];
    int length_to_copy = packet_length;

    if(packet_length > 1024)
        length_to_copy = 1024;

    memcpy(buffer, packet_data, length_to_copy); // Vulnerable line - buffer overflow

    //... processing buffered data ...
}

The code snippet above represents a simplified version of the function where the vulnerability exists. An attacker could potentially craft an SSTP packet larger than the buffer size, resulting in a buffer overflow. This could then allow the attacker to execute arbitrary code on the server.

Exploit Details

One possible exploit would involve an attacker creating a malicious SSTP packet containing shellcode. This shellcode will be executed on the target machine running the Windows RRAS service.

After crafting the malicious SSTP packet, the attacker would then send this packet to the target RRAS server over the internet. Once the server processes this packet, a buffer overflow (as discussed earlier) occurs, and the malicious code within the packet would be executed on the target machine, giving the attacker control over the RRAS server.

Original References

1. Microsoft Security Advisory for CVE-2024-26179
2. Original Research and Analysis by ESET

Conclusion

The CVE-2024-26179 is a critical Windows RRAS remote code execution vulnerability that should be addressed immediately. If left unprotected, an attacker could exploit this vulnerability to gain control over your machine. Stay safe by ensuring that your Windows systems are up-to-date with the latest security patches and updates. Additionally, follow security best practices such as enabling firewalls, using strong passwords, and disabling unnecessary services to further protect your systems.

Timeline

Published on: 04/09/2024 17:15:36 UTC
Last modified on: 04/10/2024 13:24:00 UTC