CVE-2024-49532 - Out-of-Bounds Read in Acrobat Reader Exposes Sensitive Memory

Adobe Acrobat Reader is, hands down, the world’s most popular PDF software. But with great popularity comes a huge target surface for hackers. If you're reading PDFs on your Windows PC (or even Mac), chances are you're using Acrobat Reader. In June 2024, a new vulnerability—CVE-2024-49532—has been disclosed, affecting several versions of Acrobat Reader, and it could let attackers peek into your computer’s memory, leaking sensitive information. Let's break it down simply and take a peek at the risk, some technical details, and how to stay safe.

What Is CVE-2024-49532?

This CVE is an out-of-bounds read vulnerability in Adobe Acrobat Reader. Specifically, the bug allows a malicious PDF to trick Acrobat Reader into reading memory chunks it shouldn’t, which could leak sensitive data—like your saved passwords, session tokens, or even system addresses usable for more severe attacks.

*All earlier versions are vulnerable too!*

*(Even if you’re on a recent version, make sure you’re up-to-date.)*

Why Does Sensitive Memory Matter?

Memory leaks can expose random bits of information, but often, that information is plenty enough for an attacker to plan the next stage of an attack—like bypassing OS-level security (think: Address Space Layout Randomization, aka ASLR). Once ASLR is bypassed, it becomes easier for hackers to launch code-execution exploits.

Technical Breakdown (In Simple Terms)

The issue comes down to how Acrobat processes certain parts of the PDF file—when it parses complex or malformed objects, it sometimes reads past the end of an allocated buffer. Here’s a simplified illustration (not the real Acrobat code) to give you a feel for what’s going wrong:

// Simplified: Don't use in production! 
void process_PDF_object(char* buffer, int bufsize, int offset) {
    // offset is controlled by attacker from PDF file
    char secret_data = buffer[offset];    // Potential risk: offset unchecked!
    // ... does stuff with secret_data
}

A malicious PDF can set offset to a number that points outside the bounds of what Acrobat is supposed to access, leaking whatever happens to be in memory at that location.

Potential Impact

- Leaking memory content (could include passwords, session tokens, or memory addresses for exploitation)

You open the malicious PDF sent by email or downloaded off the web.

2. *Under the hood:* Acrobat Reader parses the file and hits the buggy code path, reading out-of-bounds memory.
3. The content of that memory—which could include secret credentials or pointers—gets embedded back inside the PDF’s content or sent to the attacker (for example, via a remote form or JavaScript).

Hacker gains that sensitive data and can further attack your system if they wish.

*No actual code is being run yet—but this is often the first step before granting an attacker deeper system access.*

Example Payload in PDF (Pseudo-code)

<obj>
<< /Type /Annot
   /Subtype /Widget
   /Rect [  100 100]
   /AP <stream>
        ...malicious stream data causing out-of-bounds read...
   </stream>
>>
endobj

*This is only for illustration - real attack code would be more complex.*

Adobe Security Bulletin:

APSB24-30 Security updates available for Adobe Acrobat and Reader

NIST CVE Record:

CVE-2024-49532
- CERT/CC (pending):
https://www.kb.cert.org/vuls/id/ *(Search for "CVE-2024-49532")*

Security Research Breakdown:

See Project Zero's guide to info leaks and ASLR bypass for background on why this kind of leak matters.

Update Now:

Open Acrobat Reader and check for updates (*Help > Check for Updates...*). Patch releases for this bug are available on Adobe’s download page.

Consider Alternatives:

If you don’t need all Acrobat Reader’s features, simpler PDF readers (like Sumatra PDF or your browser’s built-in reader) might offer a reduced attack surface.

Final Thoughts

CVE-2024-49532 shows how even reading a document can be dangerous in the modern world. Out-of-bounds read bugs like this are often overlooked because they don’t grant instant command execution, but they lay the groundwork for sophisticated hackers to break deeper into your machine. The bottom line? Patch right away, and remember that not every attack is as obvious as malware or ransomware. Sometimes it starts with one innocent click on a PDF.


*Stay safe online—keep your software up to date, and share this post to help others stay protected. If you want to dig deeper, check out the original Adobe Security Bulletin and NIST page for more details!*

Timeline

Published on: 12/10/2024 20:15:18 UTC
Last modified on: 02/06/2025 18:28:13 UTC