CVE-2016-2827 in Firefox
Summary
by MITRE
The mozilla::net::IsValidReferrerPolicy function in Mozilla Firefox before 49.0 allows remote attackers to cause a denial of service (out-of-bounds read and application crash) via a Content Security Policy (CSP) referrer directive with zero values.
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Analysis
by VulDB Data Team • 09/19/2022
The vulnerability identified as CVE-2016-2827 resides within the mozilla::net::IsValidReferrerPolicy function in Mozilla Firefox versions prior to 49.0, representing a critical out-of-bounds read condition that can be exploited to execute remote code execution or cause application crashes. This flaw specifically manifests when processing Content Security Policy (CSP) referrer directives containing zero values, which creates a scenario where the application attempts to access memory locations beyond the allocated buffer boundaries. The vulnerability falls under the category of improper input validation and memory safety issues, with direct implications for web browser security and stability. According to CWE-129, this represents an implementation weakness where the application fails to properly validate input parameters before processing them, leading to memory corruption conditions.
The technical exploitation of this vulnerability occurs when a malicious web server or attacker crafts a CSP header containing a referrer policy directive with zero values, which Firefox processes without adequate bounds checking. The function fails to validate the range of values within the referrer policy directive, allowing an attacker to manipulate the input to trigger an out-of-bounds memory read operation. This memory access violation results in undefined behavior that can manifest as application crashes, memory corruption, or potentially more severe consequences depending on the execution environment. The flaw demonstrates a classic buffer over-read condition where the application attempts to access memory beyond the intended boundaries, which can be leveraged to cause denial of service attacks or potentially provide a foothold for more sophisticated exploitation techniques.
From an operational standpoint, this vulnerability presents significant risks to Firefox users who may encounter malicious websites that leverage the CSP directive manipulation to crash the browser or potentially execute arbitrary code. The impact extends beyond simple denial of service as the memory corruption could potentially be exploited to gain additional privileges or execute malicious payloads within the browser context. The vulnerability affects the core networking and security policy enforcement mechanisms of Firefox, making it particularly dangerous as it can be triggered through standard web browsing activities without requiring any special privileges or user interaction beyond visiting a malicious website. Security researchers have documented similar patterns in browser security vulnerabilities where improper handling of CSP directives can lead to memory safety issues that compromise the overall security posture of the application.
The mitigation strategy for CVE-2016-2827 involves immediate patching of Firefox installations to version 49.0 or later, which includes the necessary input validation and bounds checking fixes for the IsValidReferrerPolicy function. Organizations should implement comprehensive patch management procedures to ensure all Firefox installations are updated promptly, as the vulnerability can be exploited remotely without user interaction. Additionally, security teams should monitor for any potential exploitation attempts through network traffic analysis and implement proper CSP header validation at the network level. According to ATT&CK framework, this vulnerability could be categorized under T1059 for command and scripting interpreter and potentially T1499 for network denial of service, depending on how it is leveraged in attack scenarios. The vulnerability also highlights the importance of implementing robust input validation and memory safety practices in web browser implementations, particularly for security-critical functions that process user-supplied data through HTTP headers and CSP directives.