CVE-2020-6559 in Chrome
Summary
by MITRE
Use after free in presentation API in Google Chrome prior to 85.0.4183.83 allowed a remote attacker to potentially exploit heap corruption via a crafted HTML page.
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Analysis
by VulDB Data Team • 09/22/2020
The vulnerability identified as CVE-2020-6559 represents a critical use-after-free flaw within the presentation API implementation of Google Chrome browser. This vulnerability exists in versions prior to 85.0.4183.83 and enables remote attackers to potentially exploit heap corruption through maliciously crafted HTML pages. The presentation API in Chrome facilitates web applications to control external displays and presentation systems, making it a valuable target for attackers seeking to compromise browser security. The flaw occurs when the browser fails to properly manage memory references after objects have been freed from the heap, creating opportunities for malicious code execution.
The technical nature of this vulnerability aligns with CWE-416, which describes use-after-free conditions where memory is accessed after it has been freed. In the context of Chrome's presentation API, this occurs when the browser's JavaScript engine handles presentation-related objects and their lifecycle management. When a presentation session is terminated or when presentation objects are no longer needed, the memory allocated for these objects should be properly deallocated and the references should be invalidated. However, in the affected versions, the browser's memory management logic contained a flaw that allowed references to remain active even after the underlying memory had been freed, creating a window for exploitation. This type of heap corruption vulnerability is particularly dangerous because it can lead to arbitrary code execution when an attacker can manipulate the freed memory to contain malicious data.
The operational impact of CVE-2020-6559 extends beyond simple browser compromise, as it represents a potential vector for more sophisticated attacks within the attack chain defined by the MITRE ATT&CK framework. Specifically, this vulnerability could enable initial access through web-based exploitation, potentially leading to privilege escalation or lateral movement within a compromised system. Attackers could craft HTML pages that trigger the vulnerable code path when opened in Chrome, exploiting the use-after-free condition to execute malicious code with the privileges of the browser process. This makes it particularly concerning for enterprise environments where users may inadvertently visit malicious websites or receive phishing emails containing such crafted content. The vulnerability's remote exploitability means that attackers do not need physical access to the target system, making it a significant threat in modern threat landscapes where web-based attacks are increasingly common.
Mitigation strategies for CVE-2020-6559 primarily focus on immediate remediation through browser updates to version 85.0.4183.83 or later, which contains the necessary patches to address the use-after-free condition in the presentation API. Organizations should prioritize updating their Chrome installations across all endpoints, particularly in enterprise environments where browser security is critical for overall system protection. Additional mitigations include implementing web application firewalls that can detect and block malicious HTML content, deploying browser hardening policies that restrict presentation API usage, and enabling security features such as sandboxing and content security policies. From a defensive perspective, security teams should monitor for indicators of compromise related to this vulnerability, including unusual network connections or file modifications that might occur during exploitation attempts. The vulnerability also highlights the importance of regular security assessments of browser extensions and web applications that might interact with presentation APIs, as these components could provide additional attack vectors for exploitation.