CVE-2017-0176 in Windows
Summary
by MITRE
A buffer overflow in Smart Card authentication code in gpkcsp.dll in Microsoft Windows XP through SP3 and Server 2003 through SP2 allows a remote attacker to execute arbitrary code on the target computer, provided that the computer is joined in a Windows domain and has Remote Desktop Protocol connectivity (or Terminal Services) enabled.
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Analysis
by VulDB Data Team • 09/13/2024
The vulnerability identified as CVE-2017-0176 represents a critical buffer overflow flaw within the smart card authentication component of Microsoft Windows operating systems. This issue resides in the gpkcsp.dll module which handles cryptographic services for smart card operations, specifically affecting Windows XP SP3 and Windows Server 2003 SP2 systems. The flaw stems from inadequate input validation mechanisms within the smart card authentication code that fails to properly bounds-check data received during authentication processes, creating an exploitable condition that can be leveraged by remote attackers.
The technical implementation of this vulnerability occurs through the improper handling of user-supplied data within the smart card cryptographic service provider. When a remote attacker establishes a connection to a vulnerable system via Remote Desktop Protocol or Terminal Services, they can manipulate the smart card authentication process to trigger a buffer overflow condition. This occurs because the gpkcsp.dll module does not validate the length of incoming data before copying it into fixed-size buffers, allowing malicious data to overflow into adjacent memory regions. The flaw specifically affects systems that are domain-joined, as the smart card authentication process requires domain controller communication, making the attack surface more constrained but still highly dangerous.
The operational impact of CVE-2017-0176 extends beyond simple privilege escalation, as it provides attackers with complete system compromise capabilities. Successful exploitation allows remote code execution with the privileges of the targeted system, potentially enabling attackers to establish persistent backdoors, escalate privileges to SYSTEM level access, and conduct further reconnaissance within the network. The vulnerability's requirement for domain membership and RDP/Terminal Services connectivity creates a specific attack vector that security professionals must monitor closely, as it requires legitimate network access to the target system. This characteristic makes the vulnerability particularly concerning for enterprise environments where domain controllers and RDP services are commonly exposed to external networks.
Mitigation strategies for this vulnerability should focus on immediate patch application and network segmentation. Microsoft released security updates addressing this flaw through regular security patches, making patch management the primary defense mechanism. Organizations should implement strict network access controls to limit RDP access to trusted networks and employ multi-factor authentication for remote access. The vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and maps to ATT&CK technique T1075 for legitimate credentials usage and T1059 for command and scripting interpreter execution. Additional defensive measures include monitoring for unusual authentication patterns, implementing network-based intrusion detection systems, and conducting regular vulnerability assessments to identify and remediate similar issues in legacy systems. The vulnerability demonstrates the ongoing risks associated with supporting older operating systems and highlights the importance of maintaining up-to-date security patches across all enterprise environments.