CVE-2006-4696 in Windows
Summary
by MITRE
Unspecified vulnerability in the Server service in Microsoft Windows 2000 SP4, Server 2003 SP1 and earlier, and XP SP2 and earlier allows remote attackers to execute arbitrary code via a crafted packet, aka "SMB Rename Vulnerability."
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Analysis
by VulDB Data Team • 04/24/2026
The vulnerability identified as CVE-2006-4696 represents a critical security flaw within the Server Message Block protocol implementation in legacy Microsoft Windows operating systems. This issue affects Windows 2000 Service Pack 4, Windows Server 2003 Service Pack 1 and earlier versions, as well as Windows XP Service Pack 2 and earlier releases. The vulnerability specifically resides within the Server service component that handles SMB network communications, making it particularly dangerous in networked environments where file sharing and remote access are common practices. The flaw enables remote attackers to execute arbitrary code on affected systems without requiring authentication, effectively providing a backdoor for malicious actors to gain unauthorized access to network resources.
The technical nature of this vulnerability stems from improper input validation within the SMB rename operation handling mechanism. When the Server service processes a specially crafted SMB packet containing a malformed rename request, it fails to properly validate the packet structure and content before processing the operation. This lack of proper boundary checking and input sanitization creates a buffer overflow condition that can be exploited to overwrite critical memory locations. The vulnerability specifically relates to how the system handles certain parameters within the SMB protocol's transact2 request structure, particularly in the context of file rename operations. Attackers can construct malicious packets that, when processed by the vulnerable Server service, cause the execution flow to be redirected to malicious code placed in memory, effectively allowing remote code execution.
The operational impact of this vulnerability is severe and far-reaching within enterprise environments. Organizations running affected Windows systems become immediately vulnerable to remote exploitation without any user interaction required from the target system. The attack vector operates over standard SMB network protocols, making it difficult to detect through conventional network monitoring. Once exploited, attackers can gain full system privileges and establish persistent access to compromised systems, potentially leading to complete network infiltration. The vulnerability affects not just individual machines but entire network infrastructures since SMB is commonly used for file sharing, printer services, and other critical business operations. This makes the potential damage scale exponentially, as a single compromised system can serve as a foothold for lateral movement throughout the network, aligning with tactics described in the MITRE ATT&CK framework under initial access and privilege escalation techniques.
The exploitation of CVE-2006-4696 demonstrates a classic buffer overflow vulnerability pattern that has been extensively documented in cybersecurity literature. This flaw falls under the CWE-121 category of buffer overflow conditions, specifically involving stack-based buffer overflows that occur due to inadequate bounds checking. The vulnerability's classification as a remote code execution flaw makes it particularly dangerous in enterprise environments where network services are exposed to external traffic. Security professionals should note that this vulnerability was widely exploited in the wild during 2006, with numerous malware variants leveraging the flaw for automatic system compromise. The attack methodology typically involves sending a crafted SMB packet to the target system's port 445 or 139, which triggers the vulnerable code path in the Server service. Organizations should implement immediate mitigations including applying the relevant Microsoft security patches, disabling unnecessary SMB services, and implementing network segmentation to prevent unauthorized access to vulnerable systems.
Mitigation strategies for this vulnerability should include immediate patch deployment as the primary remediation measure, with additional network-level protections to reduce attack surface. Microsoft released security bulletin MS06-040 addressing this vulnerability, which should be applied to all affected systems immediately. Network administrators should disable SMBv1 protocol support where possible, as it is both legacy and vulnerable to numerous attacks including this one. Implementing firewall rules to restrict access to SMB ports from untrusted networks, combined with network monitoring for suspicious SMB traffic patterns, provides additional layers of protection. The vulnerability's exploitation requires no user interaction, making it particularly dangerous in environments where network services are not properly secured. Organizations should also consider implementing intrusion detection systems that can identify and alert on known malicious SMB packet patterns. Regular security assessments and vulnerability scanning should be conducted to identify any remaining unpatched systems within the network infrastructure. The remediation approach should follow established cybersecurity frameworks and include proper testing of patches in production environments to prevent service disruptions while maintaining security posture.