CVE-2021-44190 - Exploiting Adobe After Effects Out-of-Bounds Read to Leak Sensitive Memory

If you work with Adobe After Effects, this is a bug you should know about. CVE-2021-44190 affects versions 22. (and earlier) and 18.4.2 (and earlier), exposing users to potential sensitive memory leaks. In this exclusive deep dive, we’ll break down exactly what goes wrong, the risks, share sample code, and help you protect your projects.

What Is CVE-2021-44190?

CVE-2021-44190 is an out-of-bounds read vulnerability—this means the software reads memory outside of the intended buffer. This kind of issue can be dangerous because:

An attacker can often defeat modern protections, such as Address Space Layout Randomization (ASLR).

- The bug’s exploitable only if a user opens a crafted malicious file—so social engineering is involved.

How Does the Vulnerability Work?

This bug happens because of poor input validation in the way After Effects reads project files (e.g., AEP files). If the file has certain corrupted or unexpected values, After Effects can be tricked into reading outside the bounds of a memory buffer.

Visual Explanation

[Safe Buffer]            [Sensitive Info]
|----------------|*|
 | ---> Legal Read      Illegal Read (Attacker Wants This)

When After Effects sees a malformed project file, it might read into the sensitive info area.

Example Attack: How An Attacker Would Exploit This

While Adobe didn’t publish the details, security researchers regularly reconstruct similar bugs. Here’s a simplified proof-of-concept illustrating how the bug may be reached:

Malicious After Effects Project Example (Pseudo-code)

# Not real AEP format, but shows logic
file_content = b"...valid header..."  # Normal header info
file_content += b"\xFF\xFF\xFF\xFF"  # Large/negative value triggers OOB read

# User receives this file via phishing or download site
with open("evil_project.aep", "wb") as f:
    f.write(file_content)

# Victim opens evil_project.aep in vulnerable After Effects

In a real-world case, attacker studies the AEP file format and sets a field value so large it tricks After Effects into reading where it shouldn’t.

An attacker must

1. Create a specially crafted AEP file with corrupted fields (e.g., size/count fields).

Convince a victim to open the project using a vulnerable After Effects version.

3. When loaded, After Effects reads past the intended buffer boundary, exposing sensitive memory (such as private data or internal pointers).
4. The attacker recovers leaked data, which could help with further exploits (such as predicting memory layout for a second-stage attack, or stealing information).

Code Snippet Demonstrating Out-of-Bounds Read in C-like Language

char buffer[100];
int value_from_file = 200; // Malicious large value

// BAD: reads outside buffer, leaking sensitive memory
memcpy(user_output, buffer, value_from_file);

In this sketch, if value_from_file is set massively high by the AEP file, extra memory—potentially, secrets—gets copied out!

Why Is This Dangerous?

Memory disclosure vulnerabilities like this can often be chained with other bugs. For example, leaked memory could reveal:

Pointers showing ASLR layout

- Passwords/keys left in RAM

They are goldmines for attackers preparing more advanced exploits.

Mitigations and Fix

Adobe’s Response:  
Adobe issued a patch. Upgrading to the latest After Effects version is critical.

- Adobe Security Bulletin APSB21-115
- CVE-2021-44190 NVD Entry

Summary Table

| Version          | Vulnerable     | Fixed     |
|------------------|---------------|-----------|
| 18.4.2 and below | YES           | NO        |
| 22. and below   | YES           | NO        |
| 22.1 and above   | NO            | YES       |

Final Word

Even creative software like After Effects can be a target for crafty attackers. CVE-2021-44190 is a reminder: always update, be suspicious of files from strangers, and watch those security bulletins.

References

- Adobe Security Bulletin APSB21-115
- CVE-2021-44190 (NVD)
- After Effects Official Downloads

Timeline

Published on: 09/07/2023 14:15:00 UTC