CVE-2020-4739 in DB2 Accessories Suite
Summary
by MITRE • 11/21/2020
IBM DB2 Accessories Suite for Linux, UNIX, and Windows, DB2 for Linux, UNIX and Windows (includes DB2 Connect Server) 9.7, 10.1, 10.5, 11.1, and 11.5 could allow a local authenticated attacker to execute arbitrary code on the system, caused by DLL search order hijacking vulnerability in Microsoft Windows client. By placing a specially crafted file in a compromised folder, an attacker could exploit this vulnerability to execute arbitrary code on the system. IBM X-Force ID: 188149.
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Analysis
by VulDB Data Team • 12/09/2020
The vulnerability identified as CVE-2020-4739 represents a critical security flaw within IBM DB2 Accessories Suite and DB2 for Linux, UNIX and Windows across multiple versions including 9.7, 10.1, 10.5, 11.1, and 11.5. This vulnerability specifically targets systems running on Microsoft Windows platforms and exploits a DLL search order hijacking weakness that allows local authenticated attackers to gain unauthorized execution privileges. The flaw stems from how the Windows client component handles dynamic link library loading processes, creating an environment where malicious code can be injected and executed with system-level privileges.
The technical mechanism behind this vulnerability operates through a classic DLL hijacking attack vector where the system's dynamic link library search order is manipulated to load malicious libraries before legitimate ones. When an attacker successfully places a crafted malicious DLL file in a directory that appears earlier in the Windows search path, the system will load this malicious component instead of the intended legitimate library. This behavior occurs because Windows follows a specific search order when resolving DLL dependencies, and if certain directories are positioned ahead of system directories in this order, they become attack vectors for privilege escalation. The vulnerability is particularly dangerous as it requires only local authenticated access, making it accessible to users who already have legitimate system credentials.
From an operational impact perspective, this vulnerability creates a significant risk for organizations utilizing IBM DB2 database systems on Windows environments. Successful exploitation could lead to complete system compromise where attackers gain the ability to execute arbitrary code, escalate privileges, and potentially access sensitive database information. The attack surface is broad as it affects multiple versions of DB2 and spans across different Windows operating systems, making it a widespread concern for enterprise database administrators. The local authentication requirement means that attackers don't need to perform complex network-based attacks or exploit external vulnerabilities, as they can leverage existing user credentials to gain elevated privileges. This makes the vulnerability particularly concerning for environments where user access controls may not be properly enforced or where privileged accounts are compromised.
Organizations should implement several mitigation strategies to address this vulnerability effectively. Immediate patching of affected IBM DB2 versions represents the most effective remediation approach, as IBM has released security fixes specifically addressing this DLL hijacking issue. System administrators should also implement proper directory permissions and access controls to limit where DLL files can be placed, particularly in directories that appear in the Windows search order. The principle of least privilege should be enforced by ensuring that database service accounts operate with minimal required permissions and that system directories are properly secured. Network segmentation and monitoring controls should be implemented to detect unusual file creation patterns or unauthorized DLL loading activities. Additionally, implementing application whitelisting solutions can prevent unauthorized DLLs from executing on systems. This vulnerability aligns with CWE-427 Uncontrolled Search Path Element and is categorized under ATT&CK technique T1059 Command and Scripting Interpreter, specifically focusing on DLL side-loading attacks. Organizations should also conduct regular security assessments to identify and remediate similar search order vulnerabilities across their entire IT infrastructure, as this represents a common attack pattern used by sophisticated adversaries targeting enterprise database environments.