Executive Summary

[{'type': 'paragraph', 'content': "CVE-2017-20221 is a Cross-Site Request Forgery (CSRF) vulnerability in the Telesquare SKT LTE Router model SDT-CS3B1, firmware version 1.2.0. It allows authenticated attackers to execute arbitrary system commands on the router by exploiting missing request validation in the router's web application interface."}, {'type': 'paragraph', 'content': 'An attacker can craft malicious web pages that, when visited by a logged-in user, perform unauthorized administrative actions with router-level privileges. This happens because the router fails to properly verify the legitimacy of HTTP requests, enabling command execution with administrative rights.'}, {'type': 'paragraph', 'content': 'A proof-of-concept exploit involves sending a specially crafted HTTP GET request to the router’s system command interface at `/admin/system_command.shtml` with parameters that execute system commands such as `uname -a`.'}] [1, 2, 3, 4]

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Impact Analysis

This vulnerability allows attackers to execute arbitrary system commands on the affected router with administrative privileges if a logged-in user visits a malicious website.

• Attackers can perform unauthorized administrative actions remotely.
• It can lead to compromise of the router’s system, potentially affecting network security and stability.
• Since the router controls network traffic, attackers could manipulate or disrupt network communications.
• The vulnerability has a CVSS v4 base score of 5.3, indicating a medium severity with potential impact on integrity and limited impact on confidentiality and availability.

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Compliance Impact

I don't know

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Detection Guidance

[{'type': 'paragraph', 'content': "This vulnerability can be detected by attempting to execute arbitrary system commands on the router's web interface using crafted HTTP requests. A proof-of-concept involves sending a crafted HTTP GET request to the router’s system command interface at `/admin/system_command.shtml` with parameters such as `Command=sysCommand` and `Cmd=uname -a`."}, {'type': 'paragraph', 'content': 'If the router executes the command and returns system information (like the output of `uname -a`), it indicates the presence of the vulnerability.'}, {'type': 'list_item', 'content': 'Use a command-line tool like curl to send the test request: curl "http://<router-ip>/admin/system_command.shtml?Command=sysCommand&Cmd=uname%20-a" with appropriate authentication cookies or headers.'}, {'type': 'list_item', 'content': 'Monitor HTTP requests to the router for suspicious GET requests to `/admin/system_command.shtml` with command parameters.'}] [1, 4]

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Mitigation Strategies

[{'type': 'paragraph', 'content': "Immediate mitigation steps include restricting access to the router's web interface to trusted users only and avoiding visiting untrusted or suspicious websites while logged into the router's administration interface."}, {'type': 'paragraph', 'content': 'Since the vulnerability exploits missing request validation and CSRF, disabling remote administration or limiting it to secure networks can reduce exposure.'}, {'type': 'paragraph', 'content': 'If available, update the router firmware to a version that addresses this vulnerability or apply any vendor-provided patches.'}, {'type': 'paragraph', 'content': 'Implement network-level protections such as firewall rules to block unauthorized access to the router’s administrative interface.'}] [1, 2, 4]

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