Huawei HG532 Command Injection Vulnerability (CVE-2017-17215)

CVE-2017-17215.md

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+# Huawei HG532 Command Injection Vulnerability (CVE-2017-17215)
+
+## Introduction 
+
+Security flaws and vulnerabilities in internet connected or IoT(Internet of Things) devices can give attackers an easy way to break in, take control of systems, and even spread malware or viruses across a large span of networks. One common cause of these kinds of problems is what is known as command injection. This is when a device does not properly check the input that it receives, allowing anyone to run arbitrary commands from a remote location. This issue is known as CWE-77. This case study looks at the Huawei HG532 home router, a popular device for consumers that contained a major bug in its management feature that essentially allowed remote attackers to run their own commands. In this case study, I explain what the vulnerability (CVS-2017-17215) was, how attackers used it, and what developers can learn to prevent issues like this in the future. 
+
+## Software
+
+- **Name:** Huawei HG532 Home Router
+- **Language**: The vulnerability occurs in the router’s firmware, which includes components written in C and other low-level system languages commonly used in embedded Linux environments. 
+- **URL**: https://www.huawei.com/en/psirt/security-notices/2017/huawei-sn-20171130-01-hg532-en?utm_source=chatgpt.com 
+
+## Weakness: 
+
+Command injection occurs when software builds a system-level command using user provided input but fails to properly check or restrict what the user is allowed to enter as input. Instead of treating the input as plain text, the underlying system interprets special characters as instructions to execute additional commands, such as “;” or “&” or “|” and so on. This happens when developers concatenate strings directly into shell commands without filtering out any symbol that could lead to dangerous situations. As a result, even a small mistake, like trusting an external parameter or not escaping certain characters, can allow an attacker to break out of the intended command and insert their own instructions. 
+
+For example, if a program expects a website or URL as the input and a normal user types “example.com,” the program will behave as expected. However, if an attacker enters something like “example.com ; /etc/passwd” the system will first run the ping command and then immediately run the attacker’s command because the semicolon tells the shell to start a new instruction that it is given. This is a weakness that is very dangerous and leaves the program extremely vulnerable to attacks as it gives hackers a direct path from basic input to full command execution on the underlying system. Once this happens, the attacker can do anything they want including installing malware, gaining access to sensitive data, changing configurations, or even taking control of the whole device itself. Command injection continues to appear as an issue as it is both common and highly impactful when developers rely on unsafe command practices. 
+
+## Vulnerability
+
+**CVE-2017-17215**
+
+Due to the fact that this is a closed-source router firmware, there is no official source code found that was publicly available. This vulnerability affects the Huawei HG532 home router and is found in the device’s TF-064 management feature. TR-064 is supposed to help users manage their router from inside their home network. However, on these devices, the problem is that TR-064 services were accidentally exposed to the public internet on port 37215, meaning anyone online could send it requests. This service accepts multiple different input fields which causes the router to read and then use it during its update or configuration steps. 
+
+The problem with this is that the router’s firmware didn’t verify if the input was valid, therefore trusting input fields that it shouldn’t have trusted. Instead of checking the values for safety and validity, the router took the text exactly as the remote user provided it and built system level commands from it. Security researchers found that the device followed general patterns of taking the incoming parameter and inserting directly into a shell command. This in turn could allow attackers and hackers to download or process data files, essentially gaining access to any kind of data or information on the router. Because no validation or filtering was done, the router treated dangerous characters as normal text. 
+
+This becomes a serious issue when an attacker adds special shell characters to the input that can cause the program to run different commands. Certain characters like “;” and “&” tells the system to run extra commands and since the router didn’t block or validate the input, the attackers' commands would run with high privileges on the device. This allowed attackers to take full control of the router, which in turn allowed them to download malware, change configuration settings, and gain access to any and all information on the device. The vulnerability exists because the firmware built and executed system commands from the user-controlled input without validating it first, which opens the door to remote command executions and increased vulnerability to attacks, allowing attackers to be authenticated and send malicious data over ports and launch attacks. 
+
+## Exploit
+
+According to Huawei, “Successful exploit could lead to the remote execution of arbitrary code.” Attackers were able to exploit this vulnerability by sending special crafted requests to the router over port 37215, which was mistakenly exposed to the public internet. Because the router did not validate the values inside parameters “NewStatusURL” or “NewDownloadURL,” attackers could insert shell control characters that caused the router to run extra commands. Security researchers observed large numbers of scanning attempts across the internet, where attackers used automated scripts to find vulnerable HG532 devices to send malicious TR-065 messages to them. 
+For example, the semicolon (;) tells the system to stop the expected operation and start running the attackers’ command. Because the router passed this value directly into a system command without filtering it, the attackers’ extra instruction downloaded a second payload onto the device. Once this payload ran, the router became fully compromised. 
+	Research from Check Point and Cymulate show us that this vulnerability was heavily used to spread variants of the Mirai malware. Once infected, the router could be controlled remotely, used to launch distributed DDoS attacks, or scan the internet for more vulnerable devices that can be compromised. The exploit worked because the attackers only needed to send one TR-064 request and the router's firmware executed whatever commands were embedded in the attacker’s input. 
+
+## Fix
+
+Because the Huawei HG532 firmware is proprietary, the exact patch code is not publicly available. It is difficult to place exactly what inter changes were made to the TR-064 handler, so the detailed code modifications cannot be directly examined. However, Huawei has addressed this issue by stating ways that users and customers can protect themselves and provided correct firmware versions to customers for supported devices. They state that “customers can take the following measures to circumvent or prevent the exploit of this vulnerability: Configure the built-in file wall function. Change the default password. Deploy a firewall on the carrier side.” 
+
+Although the vendor has not released the patched source code, security advisories and standard secure coding practice suggest the fix required changes to how TR-064 service processed and executed incoming parameters. The vulnerability essentially followed a pattern in which attacker controlled fields (e.g. NewStatusURL or NewDownloadURL) were inserted directly into the system level commands without validation. A secure fix would involve adding strict input validation, rejecting unsafe characters, and removing all direct construction of shell commands from user-provided data. The expected corrected implementation would ensure that only trusted, properly formatted URLs are accepted and that command execution is performed through safe internal APIs instead of shell strings. 
+
+## Prevention
+
+Preventing command injection vulnerabilities requires a combination of secure coding practices, as well as ensuring secure deployment. On the coding side, developers should avoid building shell commands using user-controlled input. Instead, applications should validate incoming and external data and reject any unexpected or invalid characters. Ensuring acceptable formats and removing dangerous metacharacters are key ways to avoid recreating flaws like the one in CVE-2017-17215. 
+
+	Beyond the code itself, system designers and organizations should ensure that sensitive management services are never exposed to the public internet. Features such as TR-064 or device configuration endpoints should be restricted to internal networks only. As Huawei’s advisory notes, “The customers can deploy Huawei NGFWs (Next Generation Firewall) or data center firewalls, and upgrade the IPS signature database to the latest version released on December 1, 2017 to detect and defend against this vulnerability exploits initiated from the Internet.” These network layered defenses help protect older hardware or devices that may not be able to be patched quickly. 
+
+	Since outdated or unsupported hardware become much more vulnerable over time, especially once vendors stop releasing fixes, it’s essential for organizers to regularly replace older devices, apply patches promptly, and review firewall configurations to help ensure that even if coding mistakes occur, it does not remain exploitable for years. By combining secure development practices with strong operational security, similar vulnerabilities can be prevented before attackers are able to exploit them. 
+
+## Conclusion
+
+	CVE-2017-17215 shows how a single coding mistake can leave an entire program vulnerable to dangerous attacks and can lead to serious real world consequences. Because the HG532 firmware trusted external TR-064 input and inserted it directly into system commands, attackers were able to run their own code on the device from anywhere on the internet. Once exploited, attackers were able to remotely run their own code, allowing them to download malware, change settings, and ultimately compromise these devices. The widespread exploitation of this vulnerability demonstrates how dangerous command injection can be when it appears in internet facing services. 
+
+However, this case highlights how software security and operational security must work together. Even after the vulnerability became known, many routers remained unpatched or unsupported, which allowed attackers to continue to exploit them years later. Developers must avoid unsafe command practices and enforce strict input validation. Organizations must deploy secure firewalls, maintain updated firmware, and replace devices that have reached their capacity. By combining secure coding practices with responsible device management, vulnerabilities like CVE-2017-17215 can be contained before they lead to widespread compromise. 
+
+## References
+
+https://www.huawei.com/en/psirt/security-notices/2017/huawei-sn-20171130-01-hg532-en 
+https://cymulate.com/blog/huawei-hg532-remote-code-exploit/ 
+https://www.cybersecurity-help.cz/vdb/SB2017122501 
+https://research.checkpoint.com/2017/good-zero-day-skiddie/ 
+
+
+## Contributions
+
+	Tisha Kandunoori
+	Secure Software Design/Prog SWE-681-001
+	Professor/Reviewer: Dr. David Wheller
+