Software Engineering Institute

WinSCP is an open source SFTP client for Microsoft windows. It supports a file-manager user interface, and uses the SSH protocol to transfer files between hosts. If an attacker convinces a user to follow a specially crafted URL, a file may be directly transferred to the user's computer. The attacker may also be able to append information to files.

Depending on what the user interface settings of WinSCP are, user-interaction may or may not be required to complete the file transfer. This vulnerability is a result of certain command line switches being passed to WinSCP in the malicious URL.

If a victim user clicks on the specially-crafted URL, an attacker could send any chosen file to the victim's computer with access to folders that the user running WinSCP has write access to. The attacker could also append information to a file that may damage the file or make it unusable.

Upgrade

Version 3.8.2 of WinSCP has been published and contains a fix for this vulnerability. Users are encouraged to upgrade to this version of the software.

Restrict Access

Limit SSH client access to trusted servers. SSH servers usually listens on 22/tcp, but can be configured to listen on any TCP port.

Require User Interaction for File Transfers

WinSCP can be configured to notify the user of all file transfers and not automatically handle scp:// and sftp:// addresses. Users are encouraged to enable these options.