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.
February 20th, 2020
Azure Privilege Escalation Using Managed Identities
Azure Managed Identities are Azure AD objects that allow Azure virtual machines to act as users in an Azure subscription. While this may sound like a bad idea, AWS utilizes IAM instance profiles for EC2 and Lambda execution roles to accomplish very similar results, so it’s not an uncommon practice across cloud providers. In my […]
December 10th, 2019
Azure Privilege Escalation via Cloud Shell
TLDR; By default, Azure Subscription Contributors have access to all storage accounts in a subscription. These storage accounts can contain Azure Cloud Shell storage files (Linux home directories) that can contain sensitive information. By modifying these Cloud Shell files, an attacker can execute commands in the Cloud Shell sessions of other users. This can lead […]
September 12th, 2019
Maintaining Azure Persistence via Automation Accounts
In every penetration test that involves Azure, we want to escalate our privileges up to a global administrator of the tenant. Once we’ve escalated our privileges in an Azure tenant, we want to have the ability to maintain our access to each subscription and the tenant as a whole. Aside from the benefits of controlling […]
March 20th, 2019
Using Azure Automation Accounts to Access Key Vaults
This is the second post in a series of blogs that focuses around Azure Automation. Check out “Exporting Azure RunAs Certificates for Persistence” for more info on how authentication works for Automation Accounts. In this installment, we’re going to focus on making use of Automation Accounts to gain access to sensitive data stored in Key […]
February 27th, 2019
Get-AzurePasswords: Exporting Azure RunAs Certificates for Persistence
This post will be the first blog in a series that focuses around Azure Automation. I’ve recently run into a fair number of clients making use of Azure Automation Runbooks, and in many cases, the runbooks are being misconfigured. As attackers, these misconfigurations can provide us credentials, sensitive data, and some interesting points for escalation. […]
November 6th, 2018
Running PowerShell on Azure VMs at Scale
Let’s assume that you’re on a penetration test, where the Azure infrastructure is in scope (as it should be), and you have access to a domain account that happens to have “Contributor” rights on an Azure subscription. Contributor rights are typically harder to get, but we do see them frequently given out to developers, and […]
October 2nd, 2018
Anonymously Enumerating Azure Services
Microsoft makes use of a number of different domains/subdomains for each of their Azure services. We’ve previously covered some of these domains in a post about using trusted Azure domains for red team activities, but this time we’re going to focus on finding existing Azure subdomains as part of the recon process. Also building off […]
August 28th, 2018
Get-AzurePasswords: A Tool for Dumping Credentials from Azure Subscriptions
During different types of assessments (web app, network, cloud), we will run into situations where we obtain domain credentials that can be used to log into Azure subscriptions. Most commonly, we will externally guess credentials for a privileged domain user, but we’ve also seen excessive permissions in web applications that use Azure AD for authentication. […]
July 17th, 2018
Anonymously Enumerating Azure File Resources
In recent years, we have seen Microsoft Azure services gathering a larger market share in the cloud space. While they’re not seeing quite the adoption that AWS has, we are running into more clients that are using Microsoft Azure services for their operations. If everything is configured correctly, this can be totally fine, but it’s […]