CVE-2003-0870 in Web Browser
Summary
by MITRE
Heap-based buffer overflow in Opera 7.11 and 7.20 allows remote attackers to execute arbitrary code via an HREF with a large number of escaped characters in the server name.
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Analysis
by VulDB Data Team • 12/17/2024
The vulnerability identified as CVE-2003-0870 represents a critical heap-based buffer overflow affecting Opera web browsers version 7.11 and 7.20. This flaw resides in the browser's handling of hypertext reference (href) attributes within HTML documents, specifically when processing server names containing an excessive number of escaped characters. The vulnerability stems from inadequate input validation and memory management practices within the browser's parsing engine, creating a condition where maliciously crafted URLs can trigger unauthorized memory access patterns. The flaw operates by exploiting the browser's insufficient bounds checking when processing escaped character sequences in server name components of URLs, allowing attackers to overwrite adjacent memory locations on the heap.
From a technical perspective, this vulnerability manifests as a classic heap overflow condition where the Opera browser fails to properly validate the length of escaped character sequences in URL server names. When processing an href attribute containing an excessive number of escaped characters, the browser's memory allocation routines allocate insufficient space for the resulting string, leading to memory corruption that can be exploited to overwrite critical program data or execution pointers. The vulnerability is particularly dangerous because it operates in the context of a web browser, meaning that remote attackers can trigger this condition simply by crafting a malicious webpage containing the specially formatted href attribute. The flaw is categorized under CWE-121 Heap-based Buffer Overflow, which specifically addresses buffer overflows occurring in heap-allocated memory regions.
The operational impact of CVE-2003-0870 is severe and far-reaching, as it enables remote code execution capabilities without requiring any user interaction beyond visiting a malicious website. Attackers can leverage this vulnerability to execute arbitrary code with the privileges of the affected browser process, potentially leading to complete system compromise. The vulnerability affects a significant portion of web users who were running Opera versions 7.11 and 7.20 during the time this flaw existed, creating a substantial attack surface for threat actors. The exploitation process typically involves crafting a malicious URL with an excessive number of escaped characters that when processed by the vulnerable browser causes the heap overflow, which can then be leveraged to inject and execute malicious code. This vulnerability aligns with ATT&CK technique T1059.007 for Command and Scripting Interpreter and T1068 for Exploitation for Privilege Escalation, as it provides a mechanism for remote code execution that can be used to establish persistent access or escalate privileges within the victim's system.
The mitigation strategies for CVE-2003-0870 primarily involve immediate browser updates and patches from Opera, as the vulnerability was addressed through proper bounds checking and memory management improvements in subsequent browser versions. Users should upgrade to Opera 7.21 or later versions where the vulnerability has been resolved through enhanced input validation and proper memory allocation handling. Network administrators should implement web content filtering solutions to block access to known malicious domains that may contain such exploit payloads. Additionally, browser security configurations should be hardened through the implementation of security policies that restrict access to potentially dangerous web content and enable automatic updates for web browsers. Organizations should also conduct regular vulnerability assessments to identify and remediate similar issues in their web browsing environments. The vulnerability serves as a reminder of the importance of proper input validation and memory management practices in software development, particularly for applications handling untrusted input data from network sources.