CVE-2007-6523 in Web Browser
Summary
by MITRE
Algorithmic complexity vulnerability in Opera 9.50 beta and 9.x before 9.25 allows remote attackers to cause a denial of service (CPU consumption) via a crafted bitmap (BMP) file that triggers a large number of calculations and checks.
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Analysis
by VulDB Data Team • 08/02/2019
The vulnerability identified as CVE-2007-6523 represents a critical algorithmic complexity issue affecting Opera web browsers version 9.50 beta and all 9.x versions prior to 9.25. This flaw manifests as a denial of service condition that can be triggered remotely through the careful crafting of bitmap image files. The vulnerability specifically targets the browser's image processing capabilities, where the maliciously constructed bmp file causes the application to perform an excessive number of computational operations that consume disproportionate cpu resources.
This vulnerability operates through a classic algorithmic complexity attack vector where the crafted bmp file contains structures that force the browser's image parser to execute nested loops or recursive operations that scale exponentially with input size. The flaw lies in the insufficient input validation and optimization of the bitmap parsing algorithm, which fails to implement proper bounds checking or resource consumption limits during image processing. When Opera attempts to render the malicious bitmap, the parsing routine enters into computationally expensive operations that can cause the browser to consume excessive cpu cycles and potentially freeze or crash the application.
The operational impact of this vulnerability extends beyond simple browser instability as it provides remote attackers with a reliable method to disrupt service availability for affected users. Attackers can craft malicious bmp files that when loaded by the vulnerable browser will cause sustained high cpu utilization, effectively creating a denial of service condition that impacts the user's ability to browse the web normally. The vulnerability is particularly concerning because it can be triggered through standard web browsing activities, making it difficult for users to avoid the attack vector.
From a security perspective, this vulnerability aligns with CWE-400 which categorizes algorithmic complexity vulnerabilities as a significant threat to system stability and availability. The attack pattern follows typical denial of service methodologies described in the MITRE ATT&CK framework under the service disruption category. The vulnerability demonstrates how seemingly benign file formats can be weaponized to create system instability, highlighting the importance of robust input validation and resource management in multimedia processing components.
Mitigation strategies for this vulnerability primarily involve updating to Opera version 9.25 or later where the parsing logic has been corrected to handle malformed bitmap files appropriately. System administrators should also implement proper input validation at network boundaries and consider browser sandboxing techniques to limit the impact of such attacks. Additionally, users should be educated about avoiding untrusted image content and maintaining updated browser software to protect against known vulnerabilities. The fix typically involves implementing proper bounds checking in the bitmap parser and adding resource consumption limits to prevent excessive computational work during image processing operations.