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Showing posts from October, 2019

Abusing Windows 10 Narrator's 'Feedback-Hub' URI for Fileless Persistence

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Novel Accessibility Feature Abuse technique While investigating Ease of Access options in Windows 10 for new persistence techniques, I have actually found an undocumented one via 'Provide Narrator feedback' functionality. Behind the scenes the Narrator feedback consists in launching the custom handler via URI scheme ‘feedback-hub’. However, in a post exploitation scenario is possible to trivially backdoor this component with fileless payloads hosted in the registry. Even if there is no security boundary between windows logon screen and the default user desktop (indeed both part of the same window station WinSta0) the possibility of the interaction between the Narrator instance running in the environment of the locked out users and the Windows logon screen opens the chance to trigger the malicious command defined in the registry as soon as the 'Provide Narrator feedback' combination keys are pressed in the latter context. The novel technique presented in this arti