CVE-2017-7269 in IIS
Summary
by MITRE
Buffer overflow in the ScStoragePathFromUrl function in the WebDAV service in Internet Information Services (IIS) 6.0 in Microsoft Windows Server 2003 R2 allows remote attackers to execute arbitrary code via a long header beginning with "If: <http://" in a PROPFIND request, as exploited in the wild in July or August 2016.
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Analysis
by VulDB Data Team • 02/05/2025
The vulnerability identified as CVE-2017-7269 represents a critical buffer overflow flaw within the WebDAV service of Internet Information Services version 6.0 running on Microsoft Windows Server 2003 R2 systems. This vulnerability specifically affects the ScStoragePathFromUrl function which processes Uniform Resource Locator paths during WebDAV operations. The flaw manifests when the WebDAV service receives a PROPFIND request containing a specially crafted header that begins with "If: <http://", creating an exploitable condition that enables remote code execution. The vulnerability was actively exploited in the wild during the summer of 2016, demonstrating its real-world impact and the urgency of addressing such security gaps in enterprise web infrastructure.
The technical mechanism underlying this buffer overflow stems from inadequate input validation within the ScStoragePathFromUrl function. When processing the malformed header containing the "If: <http://" prefix, the function fails to properly bounds-check the input data before copying it into a fixed-size buffer. This allows attackers to overflow the allocated memory space and overwrite adjacent memory locations, potentially including return addresses and executable code segments. The vulnerability operates at the application layer within the IIS web server component, making it accessible through standard HTTP protocols and requiring no authentication for exploitation. This characteristic significantly increases the attack surface and makes the vulnerability particularly dangerous for unpatched systems.
The operational impact of CVE-2017-7269 extends beyond simple remote code execution to encompass complete system compromise and potential lateral movement within network environments. Successful exploitation allows attackers to execute arbitrary code with the privileges of the IIS service account, typically running with high system privileges on the target server. This privilege escalation capability enables attackers to establish persistent access, install backdoors, exfiltrate sensitive data, or use the compromised system as a launch point for further attacks against other network resources. The vulnerability's exploitation requires only a single malicious PROPFIND request, making it an attractive target for automated attack tools and increasing the potential for widespread compromise across unpatched Windows Server 2003 R2 environments.
Security professionals should implement multiple layers of defense to mitigate this vulnerability effectively. Immediate remediation involves applying the official Microsoft security patches released in conjunction with this vulnerability disclosure, specifically targeting the IIS 6.0 WebDAV service components. Organizations should also implement network segmentation and access controls to limit exposure of vulnerable systems to untrusted networks. The implementation of web application firewalls and intrusion detection systems can help detect and block malicious PROPFIND requests containing the characteristic "If: <http://" header patterns. Additionally, regular security assessments and vulnerability scanning should be conducted to identify any remaining vulnerable systems within the enterprise infrastructure, as this vulnerability aligns with CWE-121, which describes classic buffer overflow conditions. The attack pattern follows typical TTPs associated with initial access and privilege escalation techniques in the MITRE ATT&CK framework, particularly targeting the server-side web application attack surface. Organizations should also consider disabling unnecessary WebDAV functionality on IIS servers to reduce the attack surface, as this vulnerability specifically affects the WebDAV service components rather than the core IIS functionality.