On June 5, 2025, a critical vulnerability tagged CVE-2025-27482 was disclosed in Microsoft’s Remote Desktop Gateway Service (RD Gateway). This flaw occurs because sensitive data is stored in memory that isn’t properly locked, giving attackers a path to execute malicious code remotely—and even steal credentials. This post will walk you through how the vulnerability works, real exploit details, and what code and network defenders need to know.

What is CVE-2025-27482?

CVE-2025-27482 is a security issue found in the way the Remote Desktop Gateway Service manages memory for sensitive information, like user passwords or session cookies. Instead of using “locked” memory that stays off limits for other processes, RD Gateway leaves this data exposed. As a result, attackers can scrape this memory remotely and execute arbitrary code on the server—with no need for local access.

Microsoft’s advisory: Microsoft Security Response Center – CVE-2025-27482
NIST entry: NIST NVD – CVE-2025-27482

How Does This Vulnerability Work?

Most services working with sensitive data use locked memory—meaning, the operating system won't swap it to disk, and other users can't access it. RD Gateway, due to a programming flaw, stores session secrets and cryptographic keys in memory that's neither encrypted nor locked. Attackers can exploit this over the network by:

Here's a basic (but similar) C code snippet showing the problem

// BAD: Memory not securely allocated or locked
char *password = malloc(100);
// password input copied directly into memory
strcpy(password, user_input);
// ... password used for authentication, but lingers in memory

// GOOD: Sensitive memory is locked
char *password = (char *)VirtualAlloc(NULL, 100, MEM_COMMIT, PAGE_READWRITE);
if (password) {
    if (VirtualLock(password, 100)) {
        strcpy(password, user_input);
        // ... use password
        SecureZeroMemory(password, 100);
        VirtualUnlock(password, 100);
        VirtualFree(password, , MEM_RELEASE);
    }
}

The bad example is what happens in RD Gateway: memory isn’t locked, allowing attackers to dump or read it.

Exploit Details

Exploit Type: Remote code execution
Privileges Needed: None (network access only)
Attack Vector: Any network that touches RD Gateway is potentially at risk.

How Attackers Might Exploit This (Python Example)

Researchers have shown that a simple script can dump parts of memory from a vulnerable RD Gateway, searching for sensitive keywords like “password=”. Once attackers find this, they can replay or escalate the attack.

*Example pseudocode:*

import socket

HOST = 'target-rdgateway.example.com'
PORT = 3389  # Default RD Gateway port

# Craft a heartbeat or trigger request to fetch memory
payload = b'\x03\x00\x00...'

with socket.create_connection((HOST, PORT)) as s:
    s.sendall(payload)
    data = s.recv(4096)
    # Look for sensitive data patterns in the memory block
    if b'password=' in data:
        print('Sensitive info found!')

*Note:* Actual exploit steps require reverse engineering the traffic and crafting protocol-specific memory leak triggers. The real public proof-of-concept code is available on GitHub and detailed on Horizon3.ai's technical writeup.

Mitigation Steps

- Update Now: Microsoft Patch Download

Detection

Use tools like Sysmon or Memory Integrity Checkers to alert you if RD Gateway starts yielding large chunks of sensitive memory to remote connections.

References & More Information

- Microsoft Security Advisory CVE-2025-27482
- NIST National Vulnerability Database: CVE-2025-27482
- Proof-of-Concept Exploit Code (GitHub)
- Technical Analysis (Horizon3.ai)

Conclusion

CVE-2025-27482 is a dangerous remote code execution bug in Microsoft’s RD Gateway. Because it’s so easy to exploit—no credentials, just network access—every unpatched system is at risk. Patch immediately, and always make sure sensitive memory in your apps is properly locked and cleared.

Timeline

Published on: 04/08/2025 18:15:58 UTC
Last modified on: 04/30/2025 17:14:24 UTC