CVE-2008-2803 in Firefox
Summary
by MITRE
The mozIJSSubScriptLoader.LoadScript function in Mozilla Firefox before 2.0.0.15, Thunderbird 2.0.0.14 and earlier, and SeaMonkey before 1.1.10 does not apply XPCNativeWrappers to scripts loaded from (1) file: URIs, (2) data: URIs, or (3) certain non-canonical chrome: URIs, which allows remote attackers to execute arbitrary code via vectors involving third-party add-ons.
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Analysis
by VulDB Data Team • 03/16/2021
The vulnerability described in CVE-2008-2803 represents a critical security flaw in Mozilla's JavaScript execution environment that affected multiple browser and email client applications. This issue specifically targets the mozIJSSubScriptLoader.LoadScript function which is responsible for loading and executing JavaScript subscripts within the Mozilla platform. The flaw exists in Firefox versions prior to 2.0.0.15, Thunderbird versions prior to 2.0.0.14, and SeaMonkey versions prior to 1.1.10, creating a widespread attack surface across the Mozilla ecosystem. The vulnerability stems from insufficient security controls when processing scripts loaded from specific URI schemes, creating a pathway for malicious code execution that bypasses normal security boundaries.
The technical root cause of this vulnerability lies in the improper handling of XPCNativeWrappers within the script loading mechanism. XPCNativeWrappers serve as a security layer that isolates native JavaScript objects from potentially malicious code by preventing direct access to privileged operations. When scripts are loaded from file: URIs, data: URIs, or certain non-canonical chrome: URIs, the system fails to properly apply these wrappers, allowing attackers to escalate privileges and execute arbitrary code. This occurs because the mozIJSSubScriptLoader function does not consistently enforce security boundaries across all supported URI schemes, creating inconsistent security policies that can be exploited by remote attackers.
The operational impact of this vulnerability is severe and far-reaching, as it enables remote code execution attacks that can compromise entire user systems. Attackers can craft malicious scripts that, when loaded through third-party add-ons, bypass the normal security restrictions that should protect against privilege escalation. The vulnerability particularly affects environments where users install third-party extensions, as these add-ons often require elevated privileges to function properly and can become attack vectors when combined with this flaw. The attack vector involves leveraging the insecure script loading mechanism to inject malicious code that can then perform actions such as modifying system files, stealing user data, or establishing persistent backdoors.
This vulnerability aligns with CWE-264, which addresses permissions, privileges, and access control issues in software systems. The flaw demonstrates a classic case of insufficient privilege separation where security boundaries are not properly maintained during script execution. From an ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation and code injection, specifically targeting the execution of malicious code within legitimate application processes. The attack requires minimal user interaction beyond visiting compromised websites or installing malicious add-ons, making it particularly dangerous in real-world scenarios. Organizations and users affected by this vulnerability should immediately apply the security patches released by Mozilla, which properly implement XPCNativeWrappers across all supported URI schemes to restore proper security boundaries and prevent exploitation of this critical flaw.