CVE-2017-9391 in VeraEdge
Summary
by MITRE
An issue was discovered on Vera VeraEdge 1.7.19 and Veralite 1.7.481 devices. The device provides UPnP services that are available on port 3480 and can also be accessed via port 80 using the url "/port_3480". It seems that the UPnP services provide "request_image" as one of the service actions for a normal user to retrieve an image from a camera that is controlled by the controller. It seems that the "URL" parameter passed in the query string is not sanitized and is stored on the stack which allows an attacker to overflow the buffer. The function "LU::Generic_IP_Camera_Manager::REQ_Image" is activated when the lu_request_image is passed as the "id" parameter in query string. This function then calls "LU::Generic_IP_Camera_Manager::GetUrlFromArguments" and passes a "pointer" to the function where it will be allowed to store the value from the URL parameter. This pointer is passed as the second parameter $a2 to the function "LU::Generic_IP_Camera_Manager::GetUrlFromArguments". However, neither the callee or the caller in this case performs a simple length check and as a result an attacker who is able to send more than 1336 characters can easily overflow the values stored on the stack including the $RA value and thus execute code on the device.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 10/05/2023
The vulnerability identified in CVE-2017-9391 represents a critical buffer overflow flaw within the UPnP services of VeraEdge 1.7.19 and Veralite 1.7.481 devices, classified under CWE-121 as a stack-based buffer overflow condition. This issue manifests through the device's UPnP implementation which operates on port 3480 and can also be accessed via port 80 through the specific URL path "/port_3480". The vulnerability specifically targets the "request_image" service action that allows users to retrieve images from cameras controlled by the system. The flaw occurs when the URL parameter passed in the query string undergoes insufficient sanitization and gets stored directly on the stack, creating an exploitable condition that enables arbitrary code execution.
The technical exploitation mechanism involves the function LU::Generic_IP_Camera_Manager::REQ_Image which is triggered when the lu_request_image parameter is passed as the "id" parameter in the query string. This function subsequently invokes LU::Generic_IP_Camera_Manager::GetUrlFromArguments and passes a pointer to store the URL parameter value. The critical failure occurs at the lack of input validation, as neither the caller nor the callee performs any length checks on the URL parameter. The buffer overflow vulnerability specifically targets a stack location that can accommodate only 1336 characters, allowing attackers to exceed this limit and overwrite the return address (RA value) stored on the stack. This memory corruption directly enables attackers to redirect program execution flow and execute arbitrary code on the vulnerable device.
The operational impact of this vulnerability extends beyond simple privilege escalation as it allows attackers to gain full control over the affected devices, potentially compromising the entire home automation network. The vulnerability's accessibility through standard UPnP services makes it particularly dangerous as it requires no special authentication for exploitation. From an attack perspective, this vulnerability aligns with ATT&CK technique T1059.007 for command and scripting interpreter, where adversaries can execute arbitrary code through the overflowed stack memory. The device's role as a central controller in home automation systems means that successful exploitation could provide attackers with access to all connected devices and potentially enable further lateral movement within the network.
Mitigation strategies should focus on immediate firmware updates from Vera to address the buffer overflow condition through proper input validation and length checking mechanisms. Network segmentation should be implemented to isolate UPnP services from critical network segments, while firewall rules should restrict access to ports 3480 and 80 to trusted sources only. The implementation of input sanitization measures at the application layer, specifically within the GetUrlFromArguments function, should enforce strict parameter length validation and implement proper bounds checking to prevent stack memory corruption. Additionally, network monitoring should be enhanced to detect unusual patterns in UPnP service usage that might indicate exploitation attempts, as the vulnerability's exploitation would likely generate traffic patterns that deviate from normal device operation.