CVE-2017-9073 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 • 12/25/2020
The vulnerability described in CVE-2017-9073 represents a critical buffer overflow flaw within the smart card authentication component of Microsoft Windows operating systems. This issue specifically affects gpkcsp.dll, a crucial module responsible for handling cryptographic smart card operations within the Windows security framework. The flaw exists in Windows XP through Service Pack 3 and Windows Server 2003 through Service Pack 2, making it a legacy vulnerability that has persisted across multiple generations of Microsoft operating systems. The vulnerability's impact is particularly severe because it enables remote code execution when specific conditions are met within a Windows domain environment.
The technical nature of this vulnerability stems from improper input validation within the smart card authentication code that processes data from external sources. When a malicious actor exploits this buffer overflow, they can overwrite critical memory locations within the gpkcsp.dll module, potentially allowing them to inject and execute arbitrary code on the target system. The flaw requires that the target computer be part of a Windows domain and have Remote Desktop Protocol connectivity enabled, which creates a specific attack surface that security professionals must monitor closely. This condition is significant because it means the vulnerability can be exploited from remote locations without requiring physical access to the target system.
The operational impact of CVE-2017-9073 extends far beyond simple remote code execution, as it provides attackers with a potential pathway to establish persistent access within corporate networks. Since the vulnerability requires domain membership and RDP connectivity, it typically affects enterprise environments where these conditions are common. Attackers can leverage this flaw to escalate privileges, move laterally within the network, and potentially compromise additional systems. The vulnerability's classification under CWE-121 buffer overflow demonstrates its fundamental nature as an improper restriction of operations within a memory buffer, which is a well-documented weakness that has been addressed in numerous security frameworks and standards. This type of vulnerability aligns with ATT&CK technique T1059.007 for command and scripting interpreter, as successful exploitation would likely involve executing malicious payloads through the compromised authentication system.
Mitigation strategies for this vulnerability should focus on immediate patching of affected systems, as Microsoft has released security updates to address this specific flaw. Organizations must also implement network segmentation to limit RDP access to only necessary systems and users, reducing the attack surface. Security monitoring should include detection of unusual smart card authentication patterns and potential buffer overflow attempts within the gpkcsp.dll module. Additionally, implementing principle of least privilege access controls and disabling unnecessary RDP services on non-essential systems can significantly reduce the risk of exploitation. Network-based intrusion detection systems should be configured to monitor for patterns consistent with buffer overflow exploitation attempts, particularly those targeting the specific vulnerable module. The vulnerability's persistence across multiple Windows versions underscores the importance of maintaining comprehensive vulnerability management programs and ensuring all systems receive appropriate security updates.