Source: cve@mitre.org
Mozilla 0.9.6 allows remote attackers to cause a denial of service (CPU consumption and memory leak) via a web page with a large number of images.
Mozilla 0.9.6 is vulnerable to a denial-of-service (DoS) attack that can be triggered remotely. An attacker can exploit this vulnerability by crafting a webpage with a large number of images, leading to excessive CPU consumption and a memory leak, ultimately crashing the browser and potentially impacting the user's system. This vulnerability highlights the importance of robust resource management in web browsers.
Step 1: Payload Delivery: The attacker crafts a malicious HTML webpage. This webpage contains a large number of <img> tags, each referencing a valid or invalid image file (the validity of the image files is not critical to the exploit).
Step 2: User Interaction: The victim opens the malicious webpage using Mozilla 0.9.6.
Step 3: Image Loading Trigger: The browser begins to parse the HTML and attempts to load the images specified in the <img> tags.
Step 4: Resource Exhaustion: Due to the large number of images, the browser's image loading and rendering processes consume excessive CPU resources. Simultaneously, memory is allocated to store image data, but not properly released, leading to a memory leak.
Step 5: Denial of Service: The excessive CPU usage and memory leak cause the browser to become unresponsive, eventually crashing and resulting in a denial-of-service condition. The system may also become unstable due to the browser's resource consumption.
The root cause lies in Mozilla 0.9.6's inefficient handling of image loading and rendering. Specifically, the browser fails to properly manage resources when faced with a large number of image requests. The flaw is likely within the image loading or rendering engine, where the browser attempts to process and store image data without adequate resource limits. This leads to excessive CPU usage as the browser attempts to decode and render the images. Simultaneously, a memory leak occurs as the browser fails to release allocated memory for the images, causing the browser to consume more and more memory until it crashes. The lack of proper rate limiting or resource allocation for image processing is the core of the vulnerability.
This vulnerability is unlikely to be actively targeted by sophisticated APTs due to the age of the software. However, it could be used in opportunistic attacks or as part of a broader attack chain. CISA KEV status: Not Listed.
Monitor CPU usage of the Mozilla browser process. An abnormally high and sustained CPU load could indicate an ongoing attack.
Monitor memory usage of the Mozilla browser process. A steadily increasing memory footprint could signal a memory leak.
Analyze web server logs for requests to image files. A large number of requests from a single source could be suspicious.
Network traffic analysis: Look for a large number of HTTP GET requests for image files from a single source within a short period.
Upgrade to a more recent, patched version of Mozilla Firefox or another modern browser. This is the most effective mitigation.
If upgrading is not possible, disable JavaScript or image loading in the browser settings as a temporary workaround. This will prevent the malicious webpage from triggering the vulnerability.
Implement a web application firewall (WAF) to filter malicious requests. A WAF can be configured to block requests containing a large number of image tags.
Educate users about the risks of opening suspicious links or visiting untrusted websites.