CVE-2019-15992 in ASA
Summary
by MITRE
A vulnerability in the implementation of the Lua interpreter integrated in Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an authenticated, remote attacker to execute arbitrary code with root privileges on the underlying Linux operating system of an affected device. The vulnerability is due to insufficient restrictions on the allowed Lua function calls within the context of user-supplied Lua scripts. A successful exploit could allow the attacker to trigger a heap overflow condition and execute arbitrary code with root privileges on the underlying Linux operating system of an affected device.
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Analysis
by VulDB Data Team • 09/23/2020
This vulnerability exists within the Lua interpreter implementation of Cisco Adaptive Security Appliance and Cisco Firepower Threat Defense software products, representing a critical security flaw that enables authenticated remote code execution with root privileges. The issue stems from inadequate validation and restriction mechanisms that govern user-supplied Lua script execution contexts, creating an environment where malicious actors can exploit improper input handling to gain unauthorized system access. The vulnerability specifically targets the underlying Linux operating system of affected devices, making it particularly dangerous for network security infrastructure deployments.
The technical exploitation mechanism relies on insufficient restrictions on Lua function calls, allowing attackers to craft malicious scripts that can trigger heap overflow conditions within the interpreter's memory management system. This heap overflow vulnerability occurs when user-supplied Lua code attempts to manipulate memory regions beyond their allocated boundaries, creating opportunities for arbitrary code execution. The flaw operates at the intersection of scripting language interpretation and memory safety, where the Lua interpreter fails to properly validate or constrain the functions available to executing scripts, enabling access to dangerous system-level operations.
Operational impact assessment reveals severe consequences for organizations relying on affected Cisco security appliances, as successful exploitation would provide attackers with complete administrative control over the underlying Linux systems. This privilege escalation vulnerability allows unauthorized parties to execute commands with root privileges, potentially leading to complete system compromise, data exfiltration, and disruption of network security services. The remote attack vector means that adversaries can exploit this vulnerability without physical access to the devices, making it particularly attractive for cybercriminal operations targeting enterprise security infrastructure.
Mitigation strategies should focus on immediate software updates from Cisco to address the identified Lua interpreter flaws, implementing network segmentation to limit access to affected devices, and establishing monitoring procedures to detect anomalous Lua script execution patterns. Organizations should also consider disabling unnecessary Lua scripting capabilities when not required for operations, applying principle of least privilege configurations, and conducting comprehensive security assessments of their network infrastructure. The vulnerability aligns with CWE-122 (Heap Overflow) and CWE-254 (Security Misconfiguration) categories, with exploitation techniques potentially mapping to ATT&CK tactics including privilege escalation and command and control operations. Regular security patch management and vulnerability scanning procedures should be implemented to prevent similar issues in other interpreted language components within network security devices.