CVE-2013-6672 in Firefox
Summary
by MITRE
Mozilla Firefox before 26.0 and SeaMonkey before 2.23 on Linux allow user-assisted remote attackers to read clipboard data by leveraging certain middle-click paste operations.
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Analysis
by VulDB Data Team • 06/03/2021
This vulnerability exists in Mozilla Firefox versions prior to 26.0 and SeaMonkey versions prior to 2.23 on Linux operating systems, representing a significant security flaw that enables remote attackers to access clipboard contents through specific user interactions. The issue stems from improper handling of middle-click paste operations in the Linux environment, where the browser fails to adequately validate or sanitize clipboard data during these specific interaction patterns. The vulnerability is classified as user-assisted remote code execution because attackers must first convince users to perform specific middle-click operations, but once triggered, the malicious payload can access sensitive data stored in the system clipboard.
The technical implementation of this flaw involves the browser's clipboard handling mechanism on Linux systems, where middle-click operations are designed to paste clipboard contents. However, the code does not properly validate the clipboard data source or implement adequate access controls when processing these specific paste operations. This creates a privilege escalation path where untrusted remote content can potentially access clipboard data that may contain sensitive information such as passwords, personal identification numbers, or other confidential data that users have copied to their clipboard. The vulnerability specifically targets the Linux implementation of Firefox and SeaMonkey, as the underlying X11 clipboard system and Linux-specific browser integration patterns differ from other operating systems, making this particular attack vector unique to the Linux environment.
From an operational perspective, this vulnerability poses a serious risk to user privacy and data security, particularly in environments where users frequently copy sensitive information to their clipboard. The attack requires social engineering to trick users into performing middle-click operations on malicious web pages, but once successful, it allows attackers to access clipboard contents that may contain authentication credentials, personal information, or other sensitive data. This vulnerability aligns with CWE-200, which addresses "Information Exposure," and represents a specific implementation flaw in the clipboard access controls. The attack pattern follows the ATT&CK technique T1552.001, "Credentials in Files," as it enables attackers to harvest clipboard data that may contain sensitive credentials, though it requires user interaction to initiate the attack vector.
The impact of this vulnerability extends beyond simple information disclosure, as clipboard data often contains highly sensitive information that users actively protect. Attackers could exploit this flaw to harvest login credentials, API keys, or other authentication tokens that users have copied to their clipboard for legitimate purposes. The vulnerability is particularly concerning in enterprise environments where users may copy sensitive corporate data, financial information, or personal identifiers to their clipboard during routine operations. Organizations should implement immediate mitigations including updating to Firefox 26.0 or later and SeaMonkey 2.23 or later, as well as educating users about the risks of middle-click operations on untrusted websites. Additionally, system administrators should consider implementing browser security policies that restrict clipboard access or disable middle-click paste functionality in high-security environments, though such restrictions may impact user productivity and should be carefully balanced against security requirements.