CVE-2019-18988 is a vulnerability in TeamViewer
Published on February 7, 2020
TeamViewer Desktop through 14.7.1965 allows a bypass of remote-login access control because the same key is used for different customers' installations. It used a shared AES key for all installations since at least as far back as v7.0.43148, and used it for at least OptionsPasswordAES in the current version of the product. If an attacker were to know this key, they could decrypt protect information stored in the registry or configuration files of TeamViewer. With versions before v9.x , this allowed for attackers to decrypt the Unattended Access password to the system (which allows for remote login to the system as well as headless file browsing). The latest version still uses the same key for OptionPasswordAES but appears to have changed how the Unattended Access password is stored. While in most cases an attacker requires an existing session on a system, if the registry/configuration keys were stored off of the machine (such as in a file share or online), an attacker could then decrypt the required password to login to the system.
Known Exploited Vulnerability
This TeamViewer Desktop Bypass Remote Login vulnerability is part of CISA's list of Known Exploited Vulnerabilities. Allows a bypass of remote-login access control because the same key is used for different customers' installations.
The following remediation steps are recommended / required by May 3, 2022: Apply updates per vendor instructions.
Vulnerability Analysis
CVE-2019-18988 is exploitable with local system access, and requires small amount of user privileges. This vulnerability is consided to have a high level of attack complexity. This vulnerability is known to be actively exploited by threat actors. The potential impact of an exploit of this vulnerability is considered to be very high.
Weakness Type
Weak Password Requirements
The product does not require that users should have strong passwords, which makes it easier for attackers to compromise user accounts. Authentication mechanisms often rely on a memorized secret (also known as a password) to provide an assertion of identity for a user of a system. It is therefore important that this password be of sufficient complexity and impractical for an adversary to guess. The specific requirements around how complex a password needs to be depends on the type of system being protected. Selecting the correct password requirements and enforcing them through implementation are critical to the overall success of the authentication mechanism.
Products Associated with CVE-2019-18988
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Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.