T1056.003 - Web Portal Capture

Adversaries may install code on externally facing portals, such as a VPN login page, to capture and transmit credentials of users who attempt to log into the service. For example, a compromised login page may log provided user credentials before logging the user in to the service.

This variation on input capture may be conducted post-compromise using legitimate administrative access as a backup measure to maintain network access through External Remote Services and Valid Accounts or as part of the initial compromise by exploitation of the externally facing web service.(Citation: Volexity Virtual Private Keylogging)

Atomic Tests:

Currently, no tests are available for this technique.

Detection

File monitoring may be used to detect changes to files in the Web directory for organization login pages that do not match with authorized updates to the Web server’s content.