CVE-2016-1631 in Chrome
Summary
by MITRE
The PPB_Flash_MessageLoop_Impl::InternalRun function in content/renderer/pepper/ppb_flash_message_loop_impl.cc in the Pepper plugin in Google Chrome before 49.0.2623.75 mishandles nested message loops, which allows remote attackers to bypass the Same Origin Policy via a crafted web site.
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Analysis
by VulDB Data Team • 07/09/2022
The vulnerability identified as CVE-2016-1631 represents a critical security flaw in Google Chrome's Pepper plugin implementation that specifically affects versions prior to 49.0.2623.75. This issue resides within the PPB_Flash_MessageLoop_Impl::InternalRun function located in content/renderer/pepper/ppb_flash_message_loop_impl.cc, which is part of Chrome's Pepper plugin architecture designed to enable rich media content and applications within web browsers. The flaw manifests through improper handling of nested message loops, creating a pathway for malicious actors to circumvent fundamental web security mechanisms.
The technical nature of this vulnerability stems from the improper management of nested message loops within the Pepper plugin's message processing system. When Chrome processes nested message loops, the system should maintain proper isolation between different execution contexts to prevent cross-origin access violations. However, the flawed implementation allows an attacker to manipulate the message loop execution flow in a way that bypasses the same origin policy enforcement mechanisms. This occurs because the nested message loop handling does not properly validate or restrict access to resources across different origins, effectively creating a security boundary violation.
The operational impact of this vulnerability is severe and directly enables cross-origin resource access attacks. Remote attackers can craft malicious websites that exploit this flaw to gain unauthorized access to resources that should be restricted by the same origin policy. This capability allows for data exfiltration, cross-site scripting attacks, and potentially full system compromise depending on the target environment. The vulnerability specifically targets the renderer process of Chrome, meaning that successful exploitation could lead to complete browser sandbox escape and subsequent system access. Attackers can leverage this flaw to access sensitive information from other origins, potentially including cookies, local storage, and other browser resources that should remain isolated.
This vulnerability aligns with CWE-119, which addresses "Improper Restriction of Operations within the Bounds of a Memory Buffer," and more specifically with CWE-284, which covers "Improper Access Control." The flaw also maps to ATT&CK technique T1059.007, which involves the use of script-based attacks through web browsers. The security implications extend beyond simple privilege escalation as this vulnerability fundamentally undermines the browser's security model by allowing attackers to bypass core isolation mechanisms that protect users from malicious content. Organizations should prioritize immediate patching of affected Chrome versions and consider implementing additional network-level protections such as content filtering and web application firewalls to mitigate the risk of exploitation. The vulnerability highlights the importance of proper message loop management in browser security architectures and demonstrates how seemingly minor implementation flaws can create significant security risks in complex software systems.