CVE-2008-6995 in chrome
Summary
by MITRE
Integer underflow in net/base/escape.cc in chrome.dll in Google Chrome 0.2.149.27 allows remote attackers to cause a denial of service (browser crash) via a URI with an invalid handler followed by a "%" (percent) character, which triggers a buffer over-read, as demonstrated using an "about:%" URI.
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Analysis
by VulDB Data Team • 11/03/2024
The vulnerability described in CVE-2008-6995 represents a critical integer underflow condition within Google Chrome's URI parsing mechanism that can be exploited to trigger remote denial of service attacks. This flaw exists in the net/base/escape.cc component of chrome.dll, specifically affecting Chrome version 0.2.149.27 and potentially earlier versions. The vulnerability manifests when processing URIs that contain an invalid handler followed by a percent character, creating a scenario where the application fails to properly validate integer values during URI processing operations.
The technical exploitation of this vulnerability occurs through a carefully crafted URI string such as "about:%" which causes the browser to attempt integer underflow calculations during the URI parsing phase. This underflow condition leads to improper memory management where the application attempts to read beyond allocated buffer boundaries, resulting in a buffer over-read condition. The underlying issue stems from insufficient input validation and improper handling of edge cases in the URI parsing algorithm, particularly when dealing with malformed URI schemes that contain special characters.
The operational impact of this vulnerability extends beyond simple browser crashes, as it can be leveraged by remote attackers to disrupt user browsing sessions and potentially degrade system availability. When exploited, the vulnerability causes Chrome to crash and terminate unexpectedly, forcing users to restart their browser sessions and potentially lose unsaved work. This denial of service condition affects the overall user experience and can be particularly problematic in environments where browser stability is critical for business operations. The vulnerability's remote nature means that attackers can exploit it without requiring local system access, making it a significant security concern for widespread deployment.
From a cybersecurity perspective, this vulnerability maps directly to CWE-190, which describes integer overflow and underflow conditions, and aligns with ATT&CK technique T1499.004 for network denial of service attacks. The flaw demonstrates poor input validation practices that are commonly exploited in web browser security contexts, particularly in parsing components that handle user-supplied data. Organizations should implement immediate mitigations including browser updates to patched versions, network-level filtering of suspicious URI patterns, and user education about avoiding untrusted web content. Additionally, implementing robust input sanitization measures and memory protection mechanisms can help prevent exploitation of similar integer underflow conditions in other browser components. The vulnerability highlights the importance of thorough security testing for parsing logic and the need for comprehensive error handling in web browser applications to prevent exploitation of memory corruption vulnerabilities.