CVE-2019-4523 in DB2 High Performance Unload
Summary
by MITRE
IBM DB2 High Performance Unload load for LUW 6.1 and 6.5 is vulnerable to a buffer overflow, caused by improper bounds checking which could allow a local attacker to execute arbitrary code on the system with root privileges. IBM X-Force ID: 165481.
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Analysis
by VulDB Data Team • 01/17/2024
IBM DB2 High Performance Unload for Linux Unix Windows version 6.1 and 6.5 contains a critical buffer overflow vulnerability that stems from inadequate input validation and bounds checking mechanisms within the software's memory management routines. This flaw exists in the unload utility component that processes database records and transfers them to external storage systems. The vulnerability manifests when the application fails to properly validate the size of incoming data buffers, allowing an attacker to craft malicious input that exceeds allocated memory boundaries. The improper bounds checking occurs during the processing of data records that are being exported from the database system, creating a condition where stack or heap memory can be overwritten with attacker-controlled data.
The operational impact of this vulnerability is severe and potentially catastrophic for affected systems. A local attacker with minimal privileges can exploit this buffer overflow to execute arbitrary code with the highest system privileges available, typically root or system-level access. This privilege escalation occurs because the vulnerable code executes with elevated permissions to perform database operations, and the buffer overflow allows the attacker to overwrite critical program execution elements such as return addresses or function pointers. The attack vector requires local system access, meaning an attacker must already have some level of access to the target system, but the privilege escalation capability makes this vulnerability particularly dangerous in environments where multiple users share a single system or where initial access is gained through other means.
The technical implementation of this vulnerability aligns with common software security weaknesses categorized under CWE-121, which describes stack-based buffer overflow conditions. The flaw also relates to CWE-122, heap-based buffer overflow scenarios, and potentially CWE-787, out-of-bounds write conditions that can occur when input validation fails. From an adversarial perspective, this vulnerability maps to several ATT&CK techniques including privilege escalation through exploitation of software vulnerabilities and execution through command injection. The vulnerability's presence in IBM DB2 High Performance Unload specifically targets the database export functionality, making it particularly attractive to attackers seeking to extract sensitive data or establish persistent access to database environments. Organizations utilizing these specific versions of IBM DB2 should consider the vulnerability as a high-priority concern given its potential for remote code execution with system-level privileges.
Mitigation strategies for this vulnerability should include immediate application of IBM's official security patches and updates that address the specific buffer overflow conditions in the unload utility. System administrators should also implement additional security controls such as restricting local user access to database systems, implementing strict input validation procedures, and monitoring for unusual system behavior that might indicate exploitation attempts. Network segmentation and privilege separation can help limit the potential impact if exploitation occurs, while regular security audits of database systems should include verification that affected versions have been properly updated. Organizations should also consider implementing intrusion detection systems that can identify patterns consistent with buffer overflow exploitation attempts, particularly those targeting database management system components. The vulnerability demonstrates the critical importance of maintaining up-to-date software patches and proper input validation practices in database security implementations.