CVE-2017-7784 in Firefox
Summary
by MITRE
A use-after-free vulnerability can occur when reading an image observer during frame reconstruction after the observer has been freed. This results in a potentially exploitable crash. This vulnerability affects Thunderbird < 52.3, Firefox ESR < 52.3, and Firefox < 55.
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Analysis
by VulDB Data Team • 01/09/2021
The vulnerability identified as CVE-2017-7784 represents a critical use-after-free condition that manifests during image processing operations within Mozilla's browser and email client implementations. This flaw occurs specifically when the system attempts to access an image observer object after it has already been deallocated from memory, creating a scenario where subsequent operations on the freed memory location can lead to unpredictable behavior including arbitrary code execution. The vulnerability impacts multiple Mozilla products including Thunderbird versions prior to 52.3, Firefox Extended Support Release versions before 52.3, and standard Firefox versions before 55, indicating a widespread exposure across the Mozilla ecosystem. The technical nature of this vulnerability aligns with CWE-416, which specifically addresses use-after-free conditions where software continues to reference memory after it has been freed, creating potential exploitation vectors for attackers.
The operational impact of this vulnerability extends beyond simple application crashes, as the use-after-free condition creates opportunities for remote code execution attacks. When an attacker can manipulate the conditions leading to the image observer access after deallocation, they may be able to control the execution flow of the affected applications. This type of vulnerability is particularly dangerous because it can be exploited through web content or email attachments, allowing attackers to execute malicious code with the privileges of the affected user. The vulnerability's exploitation potential is enhanced by the fact that it occurs during normal frame reconstruction processes, making it difficult to detect and prevent through standard security measures. The ATT&CK framework categorizes this type of vulnerability under T1059.007 for command and scripting interpreter and T1068 for exploit for privilege escalation, as the initial exploitation can lead to further system compromise.
Mitigation strategies for CVE-2017-7784 primarily focus on immediate patch deployment and application updates to versions that contain the necessary memory management fixes. Mozilla released updates addressing this vulnerability in their affected products, and system administrators should prioritize immediate deployment of these patches across all affected systems. Additional protective measures include implementing strict content filtering mechanisms, enabling sandboxing features within the browsers, and deploying web application firewalls that can detect and block suspicious image processing requests. Organizations should also consider implementing memory corruption detection tools and runtime monitoring systems that can identify anomalous memory access patterns that may indicate exploitation attempts. The vulnerability highlights the importance of robust memory management practices and proper object lifecycle management in preventing such critical security flaws. Security teams should conduct thorough vulnerability assessments to identify any systems that may still be running affected versions and implement automated patch management solutions to ensure continuous protection against similar memory-related vulnerabilities.