Abstract

In Windows 10, Microsoft introduced the AntiMalware Scan Interface (AMSI), which is designed to target script based attacks and malware. Script based attacks have been lethal for enterprise security and with the advent of PowerShell, such attacks have become increasingly common.

AMSI targets malicious scripts written in PowerShell, VBScript, JScript, etc. It drastically improves detection and the blocking rate of malicious scripts. When a piece of code is submitted for execution to the scripting host, AMSI steps in and scans the code for malicious content. What makes AMSI effective is that no matter how obfuscated the code is, it needs to be presented to the script host in clear text and unobfuscated. Moreover, since the code is submitted to AMSI just before execution, it doesn’t matter if the code comes from disk, memory or was entered interactively. AMSI is an open interface and MS says any application will be able to call its APIs. Currently Windows Defender uses it on Windows 10.

Has Microsoft finally killed script-based attacks? Or are there even ways to bypass AMSI?

The talk will be full of live demonstrations.