CVE-2009-0086 in Windows
Summary
by MITRE
Integer underflow in Windows HTTP Services (aka WinHTTP) in Microsoft Windows 2000 SP4, XP SP2 and SP3, Server 2003 SP1 and SP2, Vista Gold and SP1, and Server 2008 allows remote HTTP servers to execute arbitrary code via crafted parameter values in a response, related to error handling, aka "Windows HTTP Services Integer Underflow Vulnerability."
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Analysis
by VulDB Data Team • 09/05/2019
The vulnerability identified as CVE-2009-0086 represents a critical integer underflow flaw within Microsoft Windows HTTP Services commonly known as WinHTTP. This security weakness affects multiple versions of Microsoft Windows operating systems including Windows 2000 Service Pack 4, Windows XP Service Packs 2 and 3, Windows Server 2003 Service Packs 1 and 2, Windows Vista Gold and Service Pack 1, and Windows Server 2008. The vulnerability stems from improper error handling mechanisms within the HTTP parsing components that process responses from remote HTTP servers. The integer underflow occurs when the system processes crafted parameter values in HTTP responses, creating a condition where a signed integer value becomes unexpectedly negative when it should remain positive, leading to unpredictable behavior in memory allocation and buffer management operations.
The technical exploitation of this vulnerability leverages the fundamental flaw in how WinHTTP handles certain HTTP response parameters that trigger integer underflow conditions during memory calculations. When a remote HTTP server sends specially crafted response data containing manipulated numerical values, the WinHTTP component performs arithmetic operations that result in integer underflow, causing the system to allocate insufficient memory buffers or manipulate memory pointers incorrectly. This flaw falls under CWE-191, which specifically addresses integer underflow conditions, and aligns with the broader category of CWE-190, integer overflow and underflow conditions. The vulnerability creates a scenario where attackers can manipulate the system's memory management routines through carefully constructed HTTP responses, potentially leading to memory corruption that can be exploited to execute arbitrary code with the privileges of the affected process.
From an operational impact perspective, this vulnerability poses significant risks to enterprise environments as it allows remote code execution without requiring authentication or user interaction. The attack surface extends to any system running affected Windows versions that process HTTP responses, making it particularly dangerous for web servers, client machines, and systems that interact with external HTTP services. The vulnerability can be exploited through various attack vectors including web browsing, email attachments, or any scenario where the affected system processes HTTP responses from untrusted sources. According to ATT&CK framework, this vulnerability maps to T1210 - Exploitation of Remote Services and T1059 - Command and Scripting Interpreter, as it enables attackers to execute malicious code remotely through HTTP services. The exploitability of this vulnerability is enhanced by the fact that it requires no special privileges or user interaction, making it particularly attractive to threat actors seeking to compromise systems silently.
Mitigation strategies for CVE-2009-0086 should focus on immediate patch deployment through Microsoft's security updates, which address the integer underflow condition in WinHTTP components. Organizations should implement network segmentation and firewall rules to limit unnecessary HTTP traffic to affected systems, particularly those running older Windows versions. Additional protective measures include disabling unnecessary HTTP services, implementing application whitelisting policies, and monitoring network traffic for suspicious HTTP response patterns that might indicate exploitation attempts. Security professionals should also consider deploying intrusion detection systems that can identify anomalous HTTP traffic patterns associated with this vulnerability. The vulnerability demonstrates the importance of proper input validation and error handling in system components, as recommended by OWASP Top 10 and NIST cybersecurity guidelines, emphasizing that developers must ensure all integer operations include proper bounds checking and overflow/underflow protection mechanisms to prevent similar security flaws in future implementations.