CVE-2016-5934 in Tivoli Storage Manager Fastback
Summary
by MITRE
IBM Tivoli Storage Manager FastBack installer could allow a remote attacker to execute arbitrary code on the system. By placing a specially-crafted DLL in the victim's path, an attacker could exploit this vulnerability when the installer is executed to run arbitrary code on the system with privileges of the victim.
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Analysis
by VulDB Data Team • 08/12/2020
The vulnerability identified as CVE-2016-5934 resides within the IBM Tivoli Storage Manager FastBack installer, representing a critical security flaw that enables remote code execution through a technique known as dynamic link library (dll) hijacking. This vulnerability operates under the weakness category of CWE-427 Uncontrolled Search Path Element, where the installer fails to properly validate the paths from which it loads dynamic libraries, creating an exploitable condition that allows attackers to inject malicious code. The flaw specifically manifests when the vulnerable installer process executes and searches for required dll files in the system path without adequate verification of source authenticity, making it susceptible to manipulation by adversaries who can place malicious dll files in strategic locations.
The technical exploitation of this vulnerability follows a precise attack pattern that aligns with the ATT&CK framework's technique T1059.001 Command and Scripting Interpreter and T1068 Exploitation for Privilege Escalation. Attackers can craft malicious dll files with names that match those expected by the FastBack installer and place them in directories that appear earlier in the system's PATH environment variable than the legitimate installation directory. When a victim executes the vulnerable installer, the system loads the attacker-controlled dll instead of the legitimate one, resulting in arbitrary code execution with the privileges of the user running the installer. This privilege escalation mechanism is particularly dangerous because it can be exploited by attackers with minimal user interaction, potentially allowing them to gain system-level access without requiring additional authentication or specialized knowledge of the target environment.
The operational impact of CVE-2016-5934 extends beyond simple code execution, creating a persistent threat vector that can be leveraged for broader system compromise. The vulnerability affects organizations that use IBM Tivoli Storage Manager FastBack for backup and recovery operations, which are typically critical infrastructure components within enterprise environments. Once an attacker achieves code execution through this vulnerability, they can establish persistence mechanisms, escalate privileges further, and potentially move laterally within the network to access additional systems and data. The remote nature of the attack means that exploitation can occur without physical access to the target system, making it particularly concerning for organizations with distributed or remote work environments where the installer might be executed on various endpoints. The vulnerability also creates a challenge for security teams because it can be exploited through legitimate installation processes, making it difficult to distinguish between authorized and malicious installation activities.
Mitigation strategies for CVE-2016-5934 must address both the immediate vulnerability and broader security posture considerations. Organizations should prioritize patching the vulnerable installer with the latest IBM security updates, which typically include proper dll loading mechanisms that prevent path traversal attacks. Additionally, implementing the principle of least privilege for installer execution can significantly reduce the impact of successful exploitation attempts. Security controls such as application whitelisting, path integrity validation, and monitoring for suspicious dll loading activities should be deployed to detect and prevent exploitation attempts. The use of tools that enforce secure dll loading practices, such as Windows AppLocker or similar application control mechanisms, can provide additional defense layers. Network segmentation and access controls should be implemented to limit where vulnerable systems can be installed, and regular security assessments should be conducted to identify and remediate similar vulnerabilities in other enterprise software components. Organizations should also consider implementing endpoint detection and response solutions that can monitor for unusual installer behavior or dll loading patterns that may indicate exploitation attempts.