CVE-2017-7804 in Firefox
Summary
by MITRE
The destructor function for the "WindowsDllDetourPatcher" class can be re-purposed by malicious code in concert with another vulnerability to write arbitrary data to an attacker controlled location in memory. This can be used to bypass existing memory protections in this situation. Note: This attack only affects Windows operating systems. Other operating systems are not affected. This vulnerability affects Thunderbird < 52.3, Firefox ESR < 52.3, and Firefox < 55.
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Analysis
by VulDB Data Team • 11/26/2025
The vulnerability identified as CVE-2017-7804 represents a critical memory corruption issue within the WindowsDllDetourPatcher class destructor functionality that specifically targets Mozilla Firefox and Thunderbird applications. This flaw exists in the Windows operating system environment where the destructor function can be manipulated by malicious actors to overwrite arbitrary data at attacker-controlled memory addresses. The vulnerability stems from improper handling of memory cleanup operations within the detour patching mechanism that allows for potential code execution bypasses. The attack vector requires coordination with another existing vulnerability to achieve successful exploitation, making it particularly dangerous as it can leverage multiple attack surfaces simultaneously. This particular weakness affects versions of Firefox and Thunderbird that were released prior to specific security patches, with the vulnerable versions including Firefox ESR 52.2 and earlier, Firefox 54 and earlier, and Thunderbird 52.2 and earlier.
The technical implementation of this vulnerability involves the manipulation of the WindowsDllDetourPatcher class destructor which is responsible for cleaning up memory resources when objects are destroyed. Under normal circumstances, this destructor should safely release allocated memory and perform proper cleanup operations. However, the flaw allows an attacker to repurpose this destructor function to write data to arbitrary memory locations specified by the attacker. This type of memory corruption vulnerability directly relates to CWE-780, which describes improper handling of memory cleanup operations that can lead to arbitrary code execution. The vulnerability specifically targets memory protection mechanisms that are designed to prevent unauthorized data modification, making it particularly effective for bypassing modern security features such as address space layout randomization and data execution prevention. The attack requires a specific sequence of exploitation steps that leverage the destructor's behavior to achieve memory corruption, which aligns with ATT&CK technique T1055 for process injection and memory injection techniques.
The operational impact of CVE-2017-7804 extends beyond simple memory corruption as it provides attackers with a method to bypass existing security protections that are typically in place to prevent malicious code execution. When successfully exploited, this vulnerability allows attackers to write arbitrary data to locations in memory that they control, effectively enabling them to modify program behavior or inject malicious code. The vulnerability affects desktop operating systems running Windows, where the specific memory management patterns and security mechanisms differ from those on other platforms. This cross-platform limitation means that while Windows systems are vulnerable, Linux and macOS versions of the affected applications remain unaffected due to different memory management implementations and security architectures. The exploitation requires a combination of vulnerabilities to succeed, suggesting that attackers may need to chain this weakness with other exploits to achieve full compromise of affected systems. The vulnerability's impact on Firefox and Thunderbird applications is significant as these browsers and email clients are commonly used targets for phishing attacks and malware distribution, making the exploitation of this weakness particularly dangerous for end users.
Mitigation strategies for CVE-2017-7804 focus primarily on updating affected software to versions that contain patches for the memory corruption issue. Users should immediately upgrade to Firefox 52.3, Firefox ESR 52.3, or Thunderbird 52.3 and later versions where the vulnerability has been addressed. System administrators should implement comprehensive patch management procedures to ensure all affected applications are updated across enterprise environments. Additional protective measures include enabling security features such as address space layout randomization, data execution prevention, and heap metadata protection that can help mitigate exploitation attempts. Organizations should also consider implementing network-based security controls and monitoring for suspicious activities that may indicate exploitation attempts. The vulnerability highlights the importance of proper memory management in security-critical code and demonstrates how seemingly minor issues in destructor functions can lead to significant security implications. Security teams should also conduct thorough code reviews focusing on memory cleanup operations and destructor implementations to identify similar vulnerabilities in other software components. Regular security assessments and vulnerability scanning should include checks for improper memory handling patterns that could lead to similar exploitation vectors. The ATT&CK framework suggests implementing defensive measures around process injection and memory manipulation techniques as part of overall security posture improvements to protect against this type of vulnerability.