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Eibiz i-Media Server Digital Signage 3.8.0 (createUser) Authentication Bypass (Add Admin)

Critical
Advisory ID
ZSL-2020-5586
Release Date
21 August 2020
Vendor
EIBIZ Co.,Ltd. - http://www.eibiz.co.th
Affected Version
<=3.8.0
CVE
N/A
Tested On
Windows Server 2016, Windows Server 2012 R2, Windows Server 2008 R2, Apache Flex, Apache Tomcat/6.0.14, Apache-Coyote/1.1, BlazeDS Application
Summary

EIBIZ develop advertising platform for out of home media in that time the world called "Digital Signage". Because most business customers still need get outside to get in touch which products and services. Online media alone cannot serve them right place, right time.

Description

The application suffers from unauthenticated privilege escalation and arbitrary user creation vulnerability that allows authentication bypass. Once serialized, an AMF encoded object graph may be used to persist and retrieve application state or allow two endpoints to communicate through the exchange of strongly typed data. These objects are received by the server without validation and authentication and gives the attacker the ability to create any user with any role and bypass the security control in place and modify presented data on the screen/billboard.

Proof of Concept
Disclosure Timeline
26.07.2020Vulnerability discovered.
30.07.2020Vendor contacted.
20.08.2020No response from the vendor.
21.08.2020Public security advisory released.
Credits
Vulnerability discovered by Gjoko Krstic
References
Changelog
21.08.2020Initial release
19.09.2020Added reference [1], [2], [3] and [4]