CVE-2017-8408 in DCS-1130
Summary
by MITRE
An issue was discovered on D-Link DCS-1130 devices. The device provides a user with the capability of setting a SMB folder for the video clippings recorded by the device. It seems that the GET parameters passed in this request (to test if SMB credentials and hostname sent to the device work properly) result in being passed as commands to a "system" API in the function and thus result in command injection on the device. If the firmware version is dissected using binwalk tool, we obtain a cramfs-root archive which contains the filesystem set up on the device that contains all the binaries. The binary "cgibox" is the one that has the vulnerable function "sub_7EAFC" that receives the values sent by the GET request. If we open this binary in IDA-pro we will notice that this follows a ARM little endian format. The function sub_7EAFC in IDA pro is identified to be receiving the values sent in the GET request and the value set in GET parameter "user" is extracted in function sub_7E49C which is then passed to the vulnerable system API call.
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Analysis
by VulDB Data Team • 06/29/2020
The vulnerability identified in CVE-2017-8408 represents a critical command injection flaw affecting D-Link DCS-1130 security cameras, where the device's improper handling of user-supplied input creates a pathway for remote code execution. This issue stems from the device's SMB configuration functionality that allows users to specify network folder locations for recorded video clips. The vulnerability manifests when the device processes GET parameters used to test SMB credential validity, directly passing these parameters to a system API without proper sanitization or validation. The affected device architecture utilizes an ARM little endian processor running a cramfs-root filesystem, where the vulnerable component resides within the cgibox binary. This binary contains the function sub_7EAFC which serves as the primary attack vector, receiving input from GET requests and subsequently invoking system API calls that execute arbitrary commands on the device. The vulnerability is particularly concerning as it allows attackers to bypass authentication mechanisms and execute arbitrary code with the privileges of the device itself, effectively compromising the entire security ecosystem of the surveillance camera. The attack surface is further expanded by the fact that this vulnerability exists in the device's web interface, making it accessible to remote attackers without requiring physical access or prior authentication.
The technical exploitation of this vulnerability follows a well-defined pattern that aligns with CWE-77 and CWE-88 categories, representing command injection through improper input validation. The function sub_7E49C extracts the "user" parameter from GET requests and passes this unvalidated data to the vulnerable system API, creating a direct code execution path. This design flaw violates fundamental security principles of input sanitization and proper parameter handling, as demonstrated by the binary analysis conducted using IDA Pro. The ARM architecture of the device means that attackers can potentially leverage existing ARM-based exploit development techniques to craft payloads that exploit the command injection vulnerability. The vulnerability's persistence across firmware versions indicates a systemic design flaw rather than a simple coding error, suggesting that similar issues may exist in other components of the device's firmware. The use of the cramfs filesystem, while providing some level of protection through its read-only nature, does not prevent the execution of malicious commands through the vulnerable API calls, making the device's security model fundamentally flawed.
The operational impact of this vulnerability extends beyond simple unauthorized access, as it enables complete compromise of the affected devices and potentially allows attackers to establish persistent backdoors or use the cameras as entry points for broader network infiltration. Once exploited, attackers can modify device configurations, access recorded video footage, or even use the device as a pivot point for attacking other systems within the local network. The vulnerability's presence in the web interface means that attackers can potentially scale their attacks across multiple devices simultaneously, especially in environments where multiple D-Link DCS-1130 cameras are deployed. Organizations relying on these devices for security monitoring face significant risks, as the compromised cameras can be used to gather intelligence on network topology, user behavior, or to launch further attacks. The lack of proper input validation and the direct invocation of system APIs represent a failure in the principle of least privilege, where user-provided data is treated as executable code rather than simple configuration parameters. This vulnerability also impacts the broader IoT security landscape, as it demonstrates how embedded devices with insufficient input validation can become critical attack vectors in network security infrastructures.
Mitigation strategies for CVE-2017-8408 should prioritize immediate firmware updates from D-Link, as the vendor has released patches addressing this vulnerability. Network segmentation and firewall rules should be implemented to restrict access to the device's web interface, particularly preventing external access to port 80 and 443 where the vulnerable functionality resides. Access control measures including strong authentication, multi-factor authentication, and regular credential rotation should be enforced to minimize the attack surface. Device monitoring and logging should be enhanced to detect unusual network traffic patterns or unauthorized configuration changes that may indicate exploitation attempts. The vulnerability's nature suggests that input validation should be implemented at multiple layers, including web application firewalls and network-level filtering to prevent malicious GET parameters from reaching the vulnerable API. Security assessments should include binary analysis of embedded devices to identify similar command injection vulnerabilities in other components. Organizations should also consider implementing network access control lists that restrict communication between the cameras and other network segments, particularly preventing access to SMB shares from the camera's network zone. The ATT&CK framework categorizes this vulnerability under T1059.001 (Command and Scripting Interpreter: PowerShell) and T1059.007 (Command and Scripting Interpreter: JavaScript) as attackers can leverage command injection to execute arbitrary code, while T1078.004 (Valid Accounts: Cloud Accounts) may be relevant if the compromised device is used as a pivot point for accessing cloud-based services.