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Microsoft Office Visio, a tool many companies use to make diagrams and flowcharts, recently faced a serious security problem. This post breaks down CVE-2024-38016, showing what went wrong, how attackers could exploit it, and what you can do to stay protected.

What is CVE-2024-38016?

CVE-2024-38016 is a Remote Code Execution (RCE) vulnerability found in Microsoft Office Visio. This means an attacker could trick a victim into opening a malicious Visio file and then run their own code on the victim’s computer. In simple words: just opening the wrong file could let a hacker take control.

How Does the Exploit Work?

Microsoft Office Visio opens special files called .vsdx, .vsd, or .vsdm. If a hacker sends you a poisoned file, and you open it in Visio, the code inside could bypass protections. Here’s what could happen:

1. Creating a Malicious File: The attacker makes a Visio file containing hidden code (often a macro or embedded object).
2. Tricking the Victim: The hacker convinces someone to download and open this file—perhaps through email or a fake website.
3. Running the Code: As soon as the user opens the file, the exploit runs, possibly giving the attacker remote access or stealing information.

Sample Malicious Macro Code

Below is a basic example of what a malicious macro inside a Visio file might look like. This sample runs the Windows Calculator (calc.exe) but real-world malware would do much worse, like downloading more malware or stealing data.

' Malicious Visio Macro Example for Exploitation
Sub AutoOpen()
    Dim evil As String
    evil = "calc.exe"
    Shell evil, vbNormalFocus
End Sub

A real attack would hide this code more carefully, but you get the idea. Just opening a bad file is all it takes.

Who is at Risk?

Any user with an unpatched version of Microsoft Office Visio is in danger, especially if they open files from untrusted sources. Many business environments use Visio for system diagrams, making this a big risk for IT departments and enterprises.

How to Protect Yourself

1. Apply Updates: Microsoft released a patch. Get it from Microsoft’s Security Update Guide.
2. Enable Office Protected View: This feature opens documents from the internet in read-only mode. Go to File > Options > Trust Center > Trust Center Settings > Protected View.

Technical Details

According to Microsoft, the vulnerability allows attackers to bypass security restrictions due to improper handling of objects in memory. Attackers can craft a Visio document that exploits this flaw. Official advisory provides more details.

They send it by email as “Network Diagram” to a user.

- If the user opens it in an outdated version of Visio, the macro runs, and calculator (or in real cases, much worse) is launched.

References

- Microsoft Security Update Guide — CVE-2024-38016
- NIST NVD Entry for CVE-2024-38016

Conclusion

CVE-2024-38016 is a real threat. Update your Microsoft Office Visio now, and always be careful with files from untrusted sources. If you’re an IT professional, roll out patches fast and review macro settings. Stay safe!

Timeline

Published on: 09/19/2024 17:15:12 UTC
Last modified on: 09/24/2024 11:11:06 UTC