Directory traversal vulnerability in Yawcam webcam server
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Overview
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Affected Versions: Yawcam 0.2.6 through 0.6.0
Patched Versions: Yawcam 0.6.1
Vendor: Yawcam
Vendor URL: http://www.yawcam.com
CVE: CVE-2017-17662
Credit: David Panter, Global Relay CSOC
Status: Public
Public disclosure URL: http://www.yawcam.com/news.php

Summary
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By sending a specially crafted HTTP GET request a remote attacker can read arbitrary files on the target computer under the privileges of the Yawcam software or service.

Product Description
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Yawcam is a free webcam software with an integrated HTTP server and wide variety of features.

Severity Rating: High

Vulnerability description
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The Yamcam HTTP server contains a directory traversal vulnerability that allows attacker to read arbitrary files through a sequence in the form '.x./' or '....\x/' where x is a pattern composed of one or more (zero or more for the second pattern) of either \ or ..\ for example '.\./', '....\/' or '...\./'.

For files with no extension a single dot needs to be appended to ensure the HTTP server does not alter the request.

POC
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By sending the following string to the Yawcam HTTP server we can read the hosts file from the target machine
"GET /.\./.\./.\./.\./.\./.\./.\./windows/system32/drivers/etc/hosts."

Timeline
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2017-12-12  Vulnerability discovered
2017-12-13  Vendor contacted
2017-12-13  CVE ID assigned
2017-12-15  Vendor reply
2017-12-18  Fixed version released
2017-12-18  Vendor disclosed vulnerability