CVE-2010-0477 in Windows
Summary
by MITRE
The SMB client in Microsoft Windows Server 2008 R2 and Windows 7 does not properly handle (1) SMBv1 and (2) SMBv2 response packets, which allows remote SMB servers and man-in-the-middle attackers to execute arbitrary code via a crafted packet that causes the client to read the entirety of the response, and then improperly interact with the Winsock Kernel (WSK), aka "SMB Client Message Size Vulnerability."
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Analysis
by VulDB Data Team • 09/08/2021
The SMB Client Message Size Vulnerability identified as CVE-2010-0477 represents a critical flaw in the Server Message Block implementation within Microsoft Windows operating systems, specifically affecting Windows Server 2008 R2 and Windows 7 clients. This vulnerability stems from improper handling of both SMBv1 and SMBv2 response packets, creating a pathway for remote code execution through carefully crafted malicious packets. The flaw operates at the core of how Windows clients process SMB communications, making it particularly dangerous as it can be exploited by attackers positioned either remotely or through man-in-the-middle attacks. The vulnerability's impact extends beyond simple network communication as it directly affects the Winsock Kernel (WSK) component, which serves as a critical interface between network applications and the operating system's networking stack.
The technical exploitation of this vulnerability occurs when an SMB client receives a crafted response packet from a malicious SMB server, causing the client to read the complete response data and subsequently interact improperly with the Winsock Kernel. This improper interaction leads to memory corruption that can be leveraged by attackers to execute arbitrary code with the privileges of the affected system. The vulnerability specifically manifests when the client processes response packets that exceed normal size parameters, triggering a buffer overflow condition within the SMB client implementation. This behavior aligns with CWE-121, which describes heap-based buffer overflow conditions, and CWE-125, which addresses out-of-bounds read vulnerabilities that can lead to memory corruption. The flaw essentially allows attackers to manipulate the client's memory management routines through malformed SMB responses, creating a pathway for privilege escalation and system compromise.
From an operational perspective, this vulnerability presents significant risk to enterprise environments as SMB is a fundamental protocol for file sharing and network communication. The vulnerability can be exploited remotely without authentication, making it particularly dangerous for systems that expose SMB services to untrusted networks. Attackers can leverage this vulnerability to gain unauthorized access to systems, potentially leading to full system compromise, data exfiltration, and lateral movement within networks. The man-in-the-middle attack vector adds another layer of complexity as it allows attackers to intercept legitimate SMB communications and inject malicious responses without requiring direct network access to the target system. This vulnerability directly maps to several ATT&CK techniques including T1071.004 for application layer protocol usage and T1059 for command and scripting interpreter execution, as successful exploitation typically results in the execution of malicious payloads within the compromised system.
Organizations should implement immediate mitigations including disabling SMBv1 support on affected systems, as this protocol version is inherently vulnerable and largely obsolete. Network segmentation and firewall rules should be configured to restrict SMB traffic between trusted network segments, while also implementing proper network monitoring to detect anomalous SMB traffic patterns. Microsoft released security updates addressing this vulnerability through the regular security bulletin process, and organizations should ensure these patches are deployed immediately. Additional defensive measures include implementing network intrusion detection systems that can identify and block suspicious SMB packet patterns, enabling automatic updates for all Windows systems, and conducting regular vulnerability assessments to identify systems that may still be vulnerable. The vulnerability also highlights the importance of maintaining up-to-date network security practices and the need for organizations to have robust incident response procedures in place for handling such critical security flaws.