CVE-2021-20309 : Exploit Details and Defense Strategies

A flaw was discovered in ImageMagick that affects versions prior to 7.0.11 and 6.9.12. This vulnerability in WaveImage() function of MagickCore/visual-effects.c could lead to undefined behavior when processing a specially crafted image file. The primary risk posed by this vulnerability is to system availability.

Understanding CVE-2021-20309

ImageMagick versions before 7.0.11 and 6.9.12 are susceptible to a division by zero vulnerability in the WaveImage() function, potentially causing undefined behavior when processing malicious image files.

What is CVE-2021-20309?

CVE-2021-20309 is a vulnerability in ImageMagick that arises from a division by zero issue in the WaveImage() function. If exploited, it could result in undefined behavior when an application using ImageMagick processes a specially crafted image file.

The Impact of CVE-2021-20309

The most significant consequence of CVE-2021-20309 is the risk it poses to system availability. Attackers can potentially leverage this vulnerability to disrupt or crash systems that process malicious images.

Technical Details of CVE-2021-20309

ImageMagick versions prior to 7.0.11 and 6.9.12 contain a vulnerability in the WaveImage() function, leading to undefined behavior due to a division by zero.

Vulnerability Description

The vulnerability in ImageMagick's WaveImage() function can be triggered by submitting a specially crafted image file, potentially causing a system crash or disruption.

Affected Systems and Versions

ImageMagick versions affected include 7.0.11 and 6.9.12, making systems utilizing these versions vulnerable to exploitation of the division by zero issue in WaveImage().

Exploitation Mechanism

By submitting a crafted image file to an application leveraging ImageMagick, threat actors can trigger the division by zero flaw in the WaveImage() function, leading to undefined behavior and potential system unavailability.

Mitigation and Prevention

In response to CVE-2021-20309, it is crucial to take immediate steps to safeguard affected systems and implement long-term security practices.

Immediate Steps to Take

It is recommended to apply the latest security updates or patches provided by ImageMagick to address the vulnerability. Additionally, consider implementing network-level protections to mitigate risks associated with the flaw.

Long-Term Security Practices

To enhance overall system security, organizations should regularly update software components, conduct security assessments, and educate users on safe image processing practices.

Patching and Updates

Stay informed about security advisories and updates from ImageMagick to promptly address any vulnerabilities that may impact system availability.