CVE-2009-1923 in Windows
Summary
by MITRE
Heap-based buffer overflow in the Windows Internet Name Service (WINS) component for Microsoft Windows 2000 SP4 and Server 2003 SP2 allows remote attackers to execute arbitrary code via a crafted WINS replication packet that triggers an incorrect buffer-length calculation, aka "WINS Heap Overflow Vulnerability."
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Analysis
by VulDB Data Team • 03/17/2021
The CVE-2009-1923 vulnerability represents a critical heap-based buffer overflow in the Windows Internet Name Service component that affects Microsoft Windows 2000 Service Pack 4 and Windows Server 2003 Service Pack 2 systems. This vulnerability resides within the WINS replication mechanism, which is responsible for maintaining and synchronizing NetBIOS name registrations across a network. The flaw manifests when the system processes malformed WINS replication packets, specifically those containing incorrectly calculated buffer lengths that exceed allocated memory boundaries. The vulnerability is classified under CWE-121 as a heap-based buffer overflow, where insufficient bounds checking allows attackers to overwrite adjacent memory locations in the heap allocation region. The attack vector requires remote exploitation through network communication, making it particularly dangerous as attackers can leverage this vulnerability from outside the network perimeter without requiring authentication.
The technical implementation of this vulnerability involves the WINS service's failure to properly validate the length field within WINS replication packets before performing memory allocation operations. When a malicious packet is received, the system calculates buffer size based on the malformed length field, leading to insufficient memory allocation for the actual data payload. This incorrect buffer-length calculation creates a situation where subsequent memory writes exceed the allocated heap space, allowing attackers to overwrite critical memory structures including return addresses and function pointers. The vulnerability demonstrates characteristics consistent with the ATT&CK technique T1203 - Exploitation for Client Execution, where attackers leverage system vulnerabilities to execute arbitrary code remotely. The heap overflow can result in arbitrary code execution with the privileges of the WINS service account, typically SYSTEM level access, making it particularly attractive to threat actors seeking persistent network access.
The operational impact of CVE-2009-1923 extends beyond simple remote code execution to provide attackers with significant network compromise capabilities. Once successfully exploited, the vulnerability allows attackers to gain full control over affected systems, potentially enabling them to establish persistence mechanisms, escalate privileges, or use the compromised system as a launch point for further network reconnaissance and lateral movement. The WINS service typically runs on port 42, making it susceptible to scanning and exploitation by automated attack tools. The vulnerability affects core network infrastructure components that are essential for name resolution and network communication, potentially causing widespread disruption to network services. Organizations with multiple WINS servers may face cascading failures if the vulnerability is exploited in a replication scenario, where a single compromised server can propagate malicious packets to other WINS servers in the network. This makes the vulnerability particularly dangerous in enterprise environments where WINS is actively used for NetBIOS name resolution.
Mitigation strategies for CVE-2009-1923 should prioritize immediate patch deployment through Microsoft Security Bulletins MS09-020, which addressed the buffer overflow issue in WINS replication handling. Organizations should disable WINS services if they are not actively required in their network infrastructure, as this eliminates the attack surface entirely. Network segmentation and firewall rules can be implemented to restrict WINS replication traffic to trusted networks only, limiting exposure to external threats. The implementation of intrusion detection systems should include signature-based detection for known WINS replication packet patterns that could indicate exploitation attempts. Additionally, monitoring for unusual WINS service behavior, particularly around replication packet processing, can help identify potential exploitation activities. System hardening measures should include disabling unnecessary WINS functionality and implementing proper network access controls. The vulnerability's age and the availability of official patches make it a prime candidate for immediate remediation, as the risk of exploitation remains high given the widespread presence of unpatched systems in many enterprise environments. Security teams should also consider implementing network-based protections such as dynamic packet filtering and monitoring for anomalous WINS traffic patterns that could indicate exploitation attempts.