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Introduction

Information disclosure vulnerabilities can be just as dangerous as more overt security holes. In May 2022, Microsoft patched a noteworthy bug—CVE-2022-26930—related to the Windows Remote Access Connection Manager (RASMAN), which, if exploited, could allow attackers to gain access to sensitive system information. This post offers an easy-to-understand, exclusive breakdown of the bug, how it works, proof-of-concept hints, and practical guidance. Whether you’re a security enthusiast, Windows admin, or simply interested in the latest threats, read on for all the details.

What is Windows RASMAN?

The Remote Access Connection Manager is a critical Windows system service. It manages dial-up and VPN connections. Because of its central role in remote connectivity, any vulnerability in RASMAN could impact both individual PCs and enterprise environments.

Main Impact: Information Disclosure

Official Microsoft Advisory:  
Microsoft Security Update Guide - CVE-2022-26930

The Vulnerability Explained: How Does It Work?

CVE-2022-26930 stems from improper handling of memory objects within the RASMAN service. If a low-privilege local user can interact with RASMAN using specially crafted requests, they might read parts of memory they shouldn’t have access to, potentially leaking:

Here’s the simplified flow

1. A local, authenticated attacker interacts with the Remote Access Connection Manager using a standard or manipulated API client.
2. Due to a flaw in how RASMAN responds or allocates memory for such queries, response data may include unintended memory content.
3. This unintentional data leakage can then be harvested by the attacker (even without admin rights!).

Proof-of-Concept (PoC) Snippet

While no public, weaponized exploit is available, a simple code example can illustrate how information leaks happen via this class of bug. Here’s a simulated pseudo-PoC in C demonstrating the general logic—(not an actual exploit!)

#include <windows.h>
#include <stdio.h>

int main() {
    HANDLE hRas = LoadLibrary("rasapi32.dll");
    if (!hRas) {
        printf("Failed to load RAS library!\n");
        return 1;
    }

    // Attempt to call a RAS function expecting to get more bytes than needed.
    BYTE buffer[4096];
    DWORD size = sizeof(buffer);

    // This simulates an improperly bounded call
    DWORD ret = RasEnumEntries(NULL, NULL, (LPRASENTRYNAME)buffer, &size, &count);

    if (ret == ERROR_SUCCESS) {
        printf("Received RAS response:\n%.*s\n", size, buffer);
        // In a vulnerable system, 'buffer' could contain sensitive memory!
    } else {
        printf("RasEnumEntries failed: %d\n", ret);
    }

    FreeLibrary(hRas);
    return ;
}

Note: This sample is illustrative. Actual triggering requires careful crafting of buffer sizes and may involve more complex interaction with the RAS API layer.

Potential Exploit Scenarios

1. Credential Harvesting: A malicious user on a shared Windows computer could extract cleartext VPN credentials or config remnants.
2. Privilege Escalation: The leaked info could be combined with other attacks to escalate privileges, especially if sensitive tokens or session details are exposed.

Mitigations & Recommendations

Microsoft addressed the flaw in their May 10, 2022 updates.

Install Latest Patch:

May 2022 Windows Updates

Additional References

- Microsoft Original Advisory
- NIST NVD Entry
- Microsoft Docs: RAS APIs

Conclusion

While CVE-2022-26930 is “just” an information disclosure, it highlights how even seemingly moderate bugs can have wider security implications, especially in environments where RASMAN is active and multiple users share access. Keep your systems patched, audit access, and stay vigilant—information is often the first step to escalation.

Stay updated, stay secure!

*Questions or comments? Reply below or reach out for further discussion on securing your Windows systems against similar vulnerabilities!*

Timeline

Published on: 05/10/2022 21:15:00 UTC
Last modified on: 05/19/2022 20:38:00 UTC