Severe TeamViewer Vulnerability Let Attackers Steal System Password

A security researcher found a severe TeamViewer
vulnerability affecting Windows versions of the application 8 through 15,
allowing attackers to steal system credentials.

TeamViewer is a powerful tool for remote administration,
but that also means it’s already a prime target for hackers and other bad
actors. Vulnerabilities in TeamViewer are dangerous, and developers have to fix
them as quickly as possible.

TeamViewer recently issued a patch covering this severe
vulnerability (CVE 2020-13699) as the problem affected a vast array of
versions, including many still in operation. When exploited, the vulnerability lets
an attacker steal the system password, making it trivial to further compromise
the operating system.

“TeamViewer Desktop for Windows before 15.8.3 does
not properly quote its custom URI handlers. A malicious website could launch
TeamViewer with arbitrary parameters, as demonstrated by a teamviewer10: –play
URL,” says the CVE advisory.
“An attacker could force a victim to send an NTLM authentication request
and either relay the request or capture the hash for offline password

Bad actors could set up a phishing site with a malicious
iframe, which would launch the TeamViewer client when the victim opened the
website. What makes the vulnerability especially dangerous is that it would
happen with little input from the user.

The developers said the vulnerability doesn’t seem to be
actively used in the wild. Now that the exploit’s details are public, though, hackers
will most likely make use of it. Since TeamViewer is a popular application, it
will take a long time for people to upgrade their clients, allowing attackers
to exploit this security issue for quite a while.

The only solution is to update TeamViewer to the latest
version as soon as possible.