CVE-2017-10722 in Endoscope
Summary
by MITRE
Recently it was discovered as a part of the research on IoT devices in the most recent firmware for Shekar Endoscope that the desktop application used to connect to the device suffers from a stack overflow if more than 26 characters are passed to it as the Wi-Fi password. This application is installed on the device and an attacker who can provide the right payload can execute code on the user's system directly. Any breach of this system can allow an attacker to get access to all the data that the user has access too. The application uses a dynamic link library(DLL) called "avilib.dll" which is used by the application to send binary packets to the device that allow to control the device. One such action that the DLL provides is change password in the function "sendchangepass" which allows a user to change the Wi-Fi password on the device. This function calls a sub function "sub_75876EA0" at address 0x7587857C. The function determines which action to execute based on the parameters sent to it. The "sendchangepass" passes the datastring as the second argument which is the password we enter in the textbox and integer 2 as first argument. The rest of the 3 arguments are set to 0. The function "sub_75876EA0" at address 0x75876F19 uses the first argument received and to determine which block to jump to. Since the argument passed is 2, it jumps to 0x7587718C and proceeds from there to address 0x758771C2 which calculates the length of the data string passed as the first parameter.This length and the first argument are then passed to the address 0x7587726F which calls a memmove function which uses a stack address as the destination where the password typed by us is passed as the source and length calculated above is passed as the number of bytes to copy which leads to a stack overflow.
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Analysis
by VulDB Data Team • 10/05/2023
The vulnerability described in CVE-2017-10722 represents a critical stack overflow condition within the Shekar Endoscope desktop application firmware, specifically affecting IoT device management software. This flaw exists within the application's handling of Wi-Fi password inputs through a dynamic link library called "avilib.dll" which serves as the communication interface between the desktop application and the endoscope device. The vulnerability manifests when a user inputs more than 26 characters into the Wi-Fi password field, triggering a buffer overflow condition that can be exploited for remote code execution on the victim's system. The attack vector is particularly concerning as it requires no special privileges or physical access to the device, making it accessible to attackers who can interact with the desktop application during normal device setup or configuration processes.
The technical implementation of this vulnerability involves a complex chain of function calls within the avilib.dll library that ultimately leads to the stack overflow condition. The primary function "sendchangepass" acts as the entry point for password modification operations, which then invokes the sub-function "sub_75876EA0" at address 0x7587857C. This sub-function uses a switch-like mechanism based on the first integer argument passed to it, where the value 2 triggers execution of a specific code path. The vulnerable code path begins at address 0x7587718C and progresses through address 0x758771C2 where the length of the user-provided password string is calculated. The critical flaw occurs when this calculated length is passed to address 0x7587726F which invokes the memmove function, using a stack-based buffer as the destination and the user-supplied password as the source. This direct memory copy operation without proper bounds checking results in the stack overflow, where the excessive data overflows into adjacent stack memory locations.
The operational impact of this vulnerability extends far beyond simple application instability, as it provides a direct pathway for arbitrary code execution on the user's system. According to CWE-121, this represents a classic stack-based buffer overflow vulnerability that can be exploited to overwrite return addresses, function pointers, or other critical stack data structures. The ATT&CK framework categorizes this as a privilege escalation technique through application exploitation, where an attacker can leverage the vulnerable desktop application to gain unauthorized access to system resources. Successful exploitation could allow attackers to access all data that the user has access to, including potentially sensitive medical information stored on or accessible through the endoscope device. The vulnerability affects the integrity and confidentiality of the entire system, as it enables attackers to execute malicious code with the privileges of the logged-in user, potentially leading to persistent backdoor access, data exfiltration, or further network compromise.
Mitigation strategies for this vulnerability should focus on immediate application-level fixes and broader security enhancements. The most direct solution involves implementing proper input validation and bounds checking within the "sub_75876EA0" function, specifically limiting the password input to a safe maximum length before passing it to the memmove operation. Additionally, implementing stack canaries, address space layout randomization, and stack protection mechanisms would significantly reduce the exploitability of this vulnerability. The firmware update process for IoT devices should be strengthened to ensure that all third-party libraries like avilib.dll are regularly audited for security flaws, and that proper code review processes are implemented before deployment. Organizations should also consider network segmentation and access controls to limit the potential impact of such vulnerabilities, while implementing monitoring solutions to detect unusual network traffic patterns that might indicate exploitation attempts. The vulnerability highlights the critical importance of security-by-design principles in IoT device development and the necessity of thorough penetration testing and code auditing of all components, particularly those handling user input in embedded systems.