CVE-2017-17867 in iopsys
Summary
by MITRE
Inteno iopsys 2.0-3.14 and 4.0 devices allow remote authenticated users to execute arbitrary OS commands by modifying the leasetrigger field in the odhcpd configuration to specify an arbitrary program, as demonstrated by a program located on an SMB share. This issue existed because the /etc/uci-defaults directory was not being used to secure the OpenWrt configuration.
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Analysis
by VulDB Data Team • 07/31/2024
The vulnerability identified as CVE-2017-17867 affects Inteno iopsys firmware versions 2.0 through 3.14 and 4.0, presenting a critical command injection flaw that enables remote authenticated attackers to execute arbitrary operating system commands. This vulnerability stems from insufficient input validation and improper configuration management within the OpenWrt-based system architecture. The flaw specifically manifests when attackers manipulate the leasetrigger field in the odhcpd configuration, allowing them to specify arbitrary programs that will be executed by the system. The attack vector is particularly concerning because it requires only authenticated access, meaning that users with legitimate network credentials can escalate their privileges and gain full system control. The vulnerability demonstrates a fundamental weakness in the firmware's security model where configuration files are not properly secured through the standard OpenWrt mechanisms.
The technical implementation of this vulnerability involves the manipulation of the odhcpd daemon configuration, which is responsible for DHCP lease management in OpenWrt systems. When an attacker modifies the leasetrigger field to point to an arbitrary program, typically one hosted on an SMB share, the system executes this program with elevated privileges. This occurs because the firmware fails to properly sanitize or validate user inputs before incorporating them into system commands. The vulnerability directly relates to CWE-78, which describes improper neutralization of special elements used in OS commands, and CWE-20, which addresses improper input validation. The attack leverages the absence of proper security controls in the /etc/uci-defaults directory, which serves as the standard OpenWrt mechanism for securing configuration files and ensuring proper system initialization. This failure to utilize established security practices creates a persistent backdoor for command execution that can be exploited by authenticated users.
The operational impact of this vulnerability extends far beyond simple privilege escalation, as it allows attackers to completely compromise affected devices and potentially use them as launching points for broader network attacks. Once authenticated, an attacker can execute commands with root privileges, potentially gaining access to sensitive network data, modifying device configurations, or establishing persistent backdoors. The use of SMB shares as attack vectors demonstrates how attackers can leverage legitimate network services to deliver malicious payloads, making detection more challenging. This vulnerability affects a wide range of network infrastructure devices that rely on Inteno iopsys firmware, particularly those used in residential and small business networks where device management and security updates may be neglected. The impact is particularly severe in environments where these devices serve as network gateways or routers, as they often have access to internal network resources and can be used to pivot attacks to other systems.
Mitigation strategies for CVE-2017-17867 must address both immediate remediation and long-term security improvements. The primary fix involves ensuring that the /etc/uci-defaults directory is properly utilized to secure OpenWrt configuration files and that all user inputs are properly sanitized before being processed. Network administrators should implement strict access controls and regularly update firmware to patched versions that address this vulnerability. The remediation process requires verifying that configuration files are not writable by untrusted users and that all input validation occurs at multiple levels within the system. Organizations should also consider implementing network monitoring solutions to detect unusual command execution patterns and establish secure configuration management practices that align with the OpenWrt security best practices. Additionally, the vulnerability highlights the importance of following the ATT&CK framework's privilege escalation techniques, particularly those related to command execution and configuration manipulation, as defenders need to understand how attackers might leverage similar weaknesses in their own network infrastructure. The security community should also consider this vulnerability as part of broader firmware security assessments, particularly focusing on the proper implementation of configuration management and input validation controls that are fundamental to preventing such attacks.