CVE-2013-0777 in Firefox
Summary
by MITRE
Use-after-free vulnerability in the nsDisplayBoxShadowOuter::Paint function in Mozilla Firefox before 19.0, Thunderbird before 17.0.3, and SeaMonkey before 2.16 allows remote attackers to execute arbitrary code or cause a denial of service (heap memory corruption) via unspecified vectors.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 05/05/2021
The vulnerability identified as CVE-2013-0777 represents a critical use-after-free condition within the rendering engine of Mozilla Firefox and related products. This flaw exists in the nsDisplayBoxShadowOuter::Paint function, which handles the rendering of box shadows in web pages. The vulnerability affects versions prior to Firefox 19.0, Thunderbird 17.0.3, and SeaMonkey 2.16, making it a widespread issue across multiple Mozilla-based applications. The use-after-free condition occurs when memory that has been freed is still accessed or referenced, creating opportunities for memory corruption and potential code execution.
The technical nature of this vulnerability stems from improper memory management within the display list processing system. When rendering complex CSS box shadows, the nsDisplayBoxShadowOuter::Paint function fails to properly validate memory references after certain operations have been completed. This allows attackers to manipulate the memory state in such a way that freed memory locations are accessed, leading to heap corruption. The vulnerability is particularly dangerous because it can be triggered through web content, making it exploitable via web browsers without requiring user interaction beyond visiting a malicious website.
From an operational perspective, this vulnerability presents significant risks to users of affected software versions. Remote attackers can leverage this flaw to execute arbitrary code on vulnerable systems, potentially leading to full system compromise. The heap memory corruption can be exploited to overwrite critical memory structures or inject malicious code into the browser process. Additionally, the vulnerability can be used for denial of service attacks, where attackers can crash the browser application or cause it to become unresponsive. The attack vector involves crafting malicious web content that triggers the specific rendering path containing the vulnerability, making it particularly concerning for web-based attacks.
Security professionals should note that this vulnerability aligns with CWE-416, which describes the use of freed memory condition, and represents a classic example of heap-based buffer overflow exploitation patterns. The ATT&CK framework categorizes this type of vulnerability under privilege escalation and code execution techniques, as it allows adversaries to gain unauthorized code execution capabilities. Organizations should prioritize immediate patching of affected versions, as the vulnerability has been actively exploited in the wild. The remediation strategy involves updating to the patched versions of Firefox, Thunderbird, and SeaMonkey, which include proper memory management fixes. Additionally, implementing network-level protections such as web application firewalls and content filtering systems can provide additional defense-in-depth measures while waiting for full patch deployment.