Vulnerability in Bytello Share

The installer uses a folder that is writeable by unprivileged users to store executables and DLLs. An attacker with access to the system can manipulate the files during the installation process to gain SYSTEM privileges.

Note that the installer needs administrative rights to run. However, we were able to exploit this in a scenario where all users were able to request the installation of the software using a web interface provided by the software deployment solution. In this case, the user can trigger the execution of the installer with elevated rights and then exploit the installation process to gain SYSTEM privileges.

The vulnerability was not acknowledged by the manufacturer and it is therefore unlikely that it will be fixed. Please refer to the Mitigation section on how to protect your environment.

CVSS Score
6.7 (CVSS v3)

Affected Version
Bytello Share 5.6.0.2497

Mitigation
We recommend refraining from using the Bytello Share Installer in scenarios where an unprivileged user can trigger the installation (e.g. using a Software Kiosk).

Credits
Kolja Grassmann (cirosec GmbH)