CVE-2007-2671 in Firefox
Summary
by MITRE
Mozilla Firefox 2.0.0.3 allows remote attackers to cause a denial of service (application crash) via a long hostname in an HREF attribute in an A element, which triggers an out-of-bounds memory access.
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Analysis
by VulDB Data Team • 08/31/2018
The vulnerability identified as CVE-2007-2671 represents a critical denial of service flaw affecting Mozilla Firefox version 2.0.0.3. This issue stems from inadequate input validation within the browser's HTML parsing engine, specifically when processing hyperlinks containing excessively long hostnames. The vulnerability manifests when a maliciously crafted HTML document contains an anchor element with an HREF attribute referencing a hostname that exceeds the application's expected buffer limits. The flaw operates through a classic buffer overflow condition where the browser attempts to process the malformed hostname data beyond allocated memory boundaries, resulting in application instability and subsequent crash.
The technical implementation of this vulnerability aligns with CWE-129, which describes improper validation of length of input buffers, and more specifically with CWE-125, which addresses out-of-bounds read conditions. When Firefox encounters an anchor tag with an abnormally long hostname, the browser's internal string handling mechanisms fail to properly validate the input length before attempting to process the data. This leads to memory access violations where the application attempts to read or write beyond the allocated memory space reserved for hostname storage. The out-of-bounds memory access occurs during the parsing phase of HTML document rendering, specifically when the browser attempts to normalize or validate the URL structure. This type of vulnerability falls under the ATT&CK technique T1499.004, which involves network denial of service attacks through exploitation of application vulnerabilities, and represents a classic example of how improper input handling can lead to system instability.
The operational impact of this vulnerability extends beyond simple application crashes, as it can be leveraged by remote attackers to disrupt service availability for legitimate users. An attacker could craft malicious web pages containing the malformed anchor elements and deliver them through various vectors including phishing campaigns, compromised websites, or social engineering attacks. The vulnerability affects the browser's rendering engine and can potentially be exploited in conjunction with other techniques to create more sophisticated attacks. Users who visit compromised websites or click on malicious links containing this exploit would experience immediate browser crashes, forcing them to restart their applications and potentially lose unsaved work. The vulnerability's remote nature means that no local system compromise is required for exploitation, making it particularly dangerous in web-based attack scenarios. Organizations relying on Firefox 2.0.0.3 for business operations would face significant disruption if this vulnerability were exploited in their environments, as it could be used to systematically crash user browsers and render them unusable.
Mitigation strategies for CVE-2007-2671 primarily involve immediate software updates to patched versions of Firefox, as Mozilla released subsequent updates addressing this specific vulnerability. System administrators should implement comprehensive patch management procedures to ensure all instances of Firefox are updated to versions containing the necessary security fixes. Additionally, network administrators can deploy web filtering solutions that block access to known malicious domains or implement content inspection mechanisms that can detect and prevent the delivery of exploit payloads. Browser hardening techniques including disabling unnecessary features, implementing strict security policies, and using sandboxing mechanisms can provide additional layers of protection. Organizations should also consider implementing intrusion detection systems that can identify patterns associated with exploitation attempts and establish incident response procedures to quickly address any successful exploitation attempts. The vulnerability serves as a reminder of the critical importance of input validation and proper memory management in web browser implementations, highlighting how seemingly simple parsing operations can lead to significant security implications when not properly secured against malformed input conditions.