NetSPI Blog

Karl Fosaaen

Karl specializes in network and web application penetration testing. Karl holds a BS in Computer Science from the University of Minnesota and has over a decade of consulting experience in the computer security industry. In that time, he has worked with a variety of industries; including financial services, health care, and retail. Karl holds the Security+, CISSP, and GXPN certifications. In his spare time, Karl has volunteered at conferences including DEF CON, THOTCON, and AppSec USA. Karl has previously spoken at BsidesPDX, THOTCON, AppSec California, and DerbyCon.

Karl Fosaaen
October 29th, 2012

Exploiting Trusted Hosts in WinRM

Introduction – What is WinRM? Windows Remote Management (WinRM) is a SOAP based protocol that can be used to remotely administer machines over the network. This is a handy tool for network admins that can also be used to automate tasks securely across multiple machines. However, it is fairly easy to misconfigure the service and/or […]

Karl Fosaaen
October 22nd, 2012

Testing Applications for DLL Preloading Vulnerabilities

DLL preloading (also known as sideloading and/or hijacking) is a common vulnerability in applications. The exploitation of the vulnerability is a simple file write (or overwrite) and then you have an executable running under the context of the application. The vulnerability is fairly easy to identify and even easier to exploit. In this blog, I […]

Karl Fosaaen
October 9th, 2012

UPEK + Lenovo = Insecure Password Storage

Recently Adam Caudill and ElcomSoft identified vulnerabilities in the way that UPEK fingerprint readers store Windows passwords in the registry. Adam has released a great proof-of-concept tool to decrypt these poorly encrypted passwords. I have access to a Lenovo T420 ThinkPad that features a UPEK fingerprint reader. The ThinkVantage Fingerprint Software is also vulnerable to […]

Karl Fosaaen
May 24th, 2012

Facebook message spoofing via SMTP

In November of 2010, Facebook introduced their “” messaging option that gave users the opportunity to create their own email address. Currently, all Facebook users have the ability to claim their own email address. It’s easily accessible from the “messages” page, if your account has not already been set up for it. While […]