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The CVE-2018-4063 vulnerability is an unrestricted upload of a dangerous file type in the `upload.cgi` component of Sierra Wireless AirLink ALEOS ACEManager. An attacker with authenticated access to the device’s web interface can craft a multipart/form-data HTTP POST request to the `/cgi-bin/upload.cgi` endpoint. The vulnerability exists because the application fails to properly validate or restrict the type and extension of files being uploaded via this function. This allows a malicious actor to upload a file containing arbitrary code, such as a shell script. The uploaded file is placed in a routable directory on the device’s webserver, for example, under /www. Consequently, the attacker can then send a subsequent HTTP GET request to the URL of the uploaded file. Since the webserver has execute permissions in that directory, the embedded code within the file runs with the privileges of the web server process. This results in complete remote command execution on the underlying operating system of the AirLink gateway, granting the attacker full control over the device.
dailycve form:
Platform: Sierra Wireless AirLink
Version: Up to 4.9.3
Vulnerability: Unrestricted File Upload
Severity: Critical
date: 2018-12-11
Prediction: 2019-04-23
What Undercode Say:
Snort rule to detect exploit attempts (CVE-2018-4063) alert tcp any any -> any 80 (msg:"CVE-2018-4063 - Sierra Wireless upload.cgi RCE Attempt"; flow:to_server,established; content:"POST"; http_method; content:"/cgi-bin/upload.cgi"; http_uri; content:"multipart/form-data"; http_header; pcre:"/filename\s=\s[^;].(sh|pl|py|php)/i"; sid:48614; rev:1;) Example curl command attempting to upload a malicious file (requires authenticated session cookies) curl -X POST https://<target_ip>/cgi-bin/upload.cgi -H "Cookie: <session_cookie>" -F "file=@malicious_shell.sh"
How Exploit:
- Attacker gains authenticated access to ACEManager web interface.
- Crafts an HTTP POST request with a malicious file (e.g., a shell script) to
/cgi-bin/upload.cgi. - The vulnerable application accepts and saves the file to a webserver directory like
/www. - Attacker accesses the uploaded file via a web browser or
curl, triggering remote code execution.
Protection from this CVE:
Apply vendor patch to ALEOS version 4.9.4.p09 or later.
Restrict network access to the ACEManager interface.
Implement strong password policies for device accounts.
Disable unused services like ALEOS Application Framework.
Impact:
Complete system compromise enabling unauthorized configuration changes, data theft, and network pivoting.
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Sources:
Reported By: www.cve.org
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