How to Add a Subject Alternative Name Safely

I am writing about that PKI stuff again. I am running out of ideas for catchy introductions. So, here is a new post with old code! In Active Directory a UPN is mapped to a user automatically if it matches a user's LDAP attribute userPrincipalName (and a DNS SAN is mapped to dnsHostName).  A Windows … Continue reading How to Add a Subject Alternative Name Safely

Rogue Certificate Challenge: No Hardware Tokens, No Linux, Just a Web Server with Certificate Mapping.

I am back to my favorite security research: How to abuse certificates in a Windows / Active Directory environment! If an Active Directory integrated certification authority sign a certificate with a custom Subject Alternative Name of your choosing, you can impersonate any administrator in an AD forest. I've published two blog posts about how to … Continue reading Rogue Certificate Challenge: No Hardware Tokens, No Linux, Just a Web Server with Certificate Mapping.

Looking Back: Hacking and Defending Windows Public Key Infrastructure (ADCS)

I live at the fringes of the cybersecurity community. I have never attended infosec conferences. There will be a talk on PKI hacking at Blackhat 2021 soon: Top AD offensive security gurus are presenting comprehensive research on abusing ADCS (Active Directory Certificate Services). I only know about that, because I noticed backlinks from their article … Continue reading Looking Back: Hacking and Defending Windows Public Key Infrastructure (ADCS)

Secure Poetry: “I have been quite confident”

A poem from snippets of two postings on cybersecurity. Trying to carve words out of jargon. Details on the creative process at the bottom of the post.   I have been quite confident I have been inspired In this simple way to find both options take note of an extra stealth factor I hardly ever … Continue reading Secure Poetry: “I have been quite confident”

Injecting an EFS Recovery Agent – and Let the Virus Scanner Help You!

How can you read files encrypted with Windows's Encrypting File System if you neither have access to the owner's encryption certificate and key and nor that of a legit data recovery agent (DRA) ... but if you are a local administrator? This work is still inspired by the hackthebox machine Helpline. You were able to … Continue reading Injecting an EFS Recovery Agent – and Let the Virus Scanner Help You!

Parse Certificates Stored in the Windows Registry

You can parse the binary blobs that represent certificates stored in the Windows registry with certutil correctly, even when the Windows Explorer / GUI tells you that this is not a certificate. certutil seems to be able to handle / ignore meta data better. Once upon a time I played with the machine Ethereal provided by … Continue reading Parse Certificates Stored in the Windows Registry

Infinity

New Year's Eve 2019 seems infinitely far in the past. It was the first day news about this mysterious disease had been published in my country. Yet it seems infinitely far away at that time, somewhere in China. Today we see something glowing at the end of a weird long corridor. Despite horrible news, I … Continue reading Infinity

The RSA Algorithm

You want this: Encrypt a message to somebody else - using information that is publicly available. Somebody else should then be able to decrypt the message, using only information they have; nobody else should be able to read this information. The public key cryptography algorithm RSA does achieve this. This article is my way of … Continue reading The RSA Algorithm

Impersonating a Windows Enterprise Admin with a Certificate: Kerberos PKINIT from Linux

This is about a serious misconfiguration of a Windows Public Key Infrastructure integrated with Active Directory: If you can edit certificate templates, you can impersonate the Active Directory Forests's Enterprise Administrator by logging on with a client certificate. You have a persistent credential that will also survive the reset of this admin's password. In the … Continue reading Impersonating a Windows Enterprise Admin with a Certificate: Kerberos PKINIT from Linux

Locating Domain Controllers and Spoofing Active Directory DNS Servers

Last year, hackthebox let me test something I have always found fascinating - and scary: You can impersonate any user in a Windows Active Directory Forest if you have control over the certificate templates of an AD-integrated Windows Public Key Infrastructure: Add extended key usages for smartcard logon to the template, enroll for the certificate, … Continue reading Locating Domain Controllers and Spoofing Active Directory DNS Servers

Helpline @ hackthebox: Injecting an EFS Recovery Agent to Read Encrypted Files

Another great machine has been retired on hackthebox.eu - Helpline by @egre55! Here is my 'silly' unintended way to root the box: You can get both the encrypted user and root flag via the cumbersome web RCE alone - if you wait for a legit user to just look at the file. This is unlikely … Continue reading Helpline @ hackthebox: Injecting an EFS Recovery Agent to Read Encrypted Files

Sizzle @ hackthebox – Unintended: Getting a Logon Smartcard for the Domain Admin!

My writeup - how to pwn my favorite box on hackthebox.eu, using a (supposedly) unintended path. Sizzle - created by @mrb3n813 and @lkys37en - was the first box on HTB that had my favorite Windows Server Role - the Windows Public Key Infrastructure / Certification Authority. This CA allows a low-privileged user - amanda - … Continue reading Sizzle @ hackthebox – Unintended: Getting a Logon Smartcard for the Domain Admin!

Simple Ping Sweep, Port Scan, and Getting Output from Blind Remote Command Execution

Just dumping some quick and dirty one-liners! These are commands I had used to explore locked-down Windows and Linux machines, using bash or powershell when no other binaries were available or could be transferred to the boxes easily. Trying to ping all hosts in a subnet Linux for i in $(seq 1 254); do host=192.168.0.$i; … Continue reading Simple Ping Sweep, Port Scan, and Getting Output from Blind Remote Command Execution

Echo Unreadable Hex Characters in Windows: forfiles

How to transfer small files to a locked-down Windows machine? When there is no option to copy, ftp, or http GET a file. When powershell is blocked so that you can only use Windows cmd commands? My first choice would be to use certutil: certutil is a built-in tool for certificate and PKI management. It … Continue reading Echo Unreadable Hex Characters in Windows: forfiles

Ethereal @ hackthebox: Certificate-Related Rabbit Holes

This post is related to the 'insanely' difficult hackthebox machine Ethereal (created by egre55 and MinatoTW) that was recently retired. Beware - It is not at all a full comprehensive write-up! I zoom in on openssl, X.509 certificates, signing stuff, and related unnecessary rabbit holes that were particularly interesting to me - as somebody who … Continue reading Ethereal @ hackthebox: Certificate-Related Rabbit Holes

Certificates and PKI. The Prequel.

Some public key infrastructures run quietly in the background since years. They are half forgotten until the life of a signed file has come to an end - but then everything is on fire. In contrast to other seemingly important deadlines (Management needs this until XY or the world will come to an end!) this … Continue reading Certificates and PKI. The Prequel.

Modbus Server on Raspberry Pi as Babelfish for UVR16x2

Our main data logger is the Control and Monitoring Interface of the freely programmable controller UVR16x2. There are two pieces of hardware you need for logging - the actual control unit and the logger connected to the controller via the CAN bus. This 'architecture' might be due to historical reasons, but I like the separation … Continue reading Modbus Server on Raspberry Pi as Babelfish for UVR16x2

Unintended 2nd Order SQL Injection

Why I am not afraid of the AI / Big Data / Cloud powered robot apocalypse. SQL order injection means to run custom SQL queries through web interfaces because the input to the intended query is not sanitized, like appending the infamous ' OR '1'='1 to a user name or search term. It is 2nd … Continue reading Unintended 2nd Order SQL Injection

A Color Box. Lost in Translation

It was that time again. The Chief Engineer had rebuilt the technical room from scratch. Each piece of heavy equipment had a new place, each pipe and wire was reborn in a new incarnation (German stories here.) The control system was turned upset down as well, and thus the Data Kraken was looking at its … Continue reading A Color Box. Lost in Translation

Hacking

I am joining the ranks of self-proclaimed productivity experts: Do you feel distracted by social media? Do you feel that too much scrolling feeds transforms your mind - in a bad way? Solution: Go find an online platform that will put your mind in a different state. Go hacking on hackthebox.eu. I have been hacking … Continue reading Hacking

Cloudy Troubleshooting (2)

Unrelated to part 1 - but the same genre. Actors this time: File Cloud: A cloud service for syncing and sharing files. We won't drop a brand name, will we? Client: Another user of File Cloud. [Redacted]: Once known for reliability and as The Best Network. Dark Platform: Wannabe hackers' playground. elkement: Somebody who sometimes just wants to be an … Continue reading Cloudy Troubleshooting (2)

Infinite Loop: Theory and Practice Revisited.

I've unlocked a new achievement as a blogger, or a new milestone as a life-form. As a dinosaur telling the same old stories over and over again. I started drafting a blog post, as I always do since a while: I do it in my mind only, twist and turn in for days or weeks … Continue reading Infinite Loop: Theory and Practice Revisited.

Where Are the Files? [Winsol – UVR16x2]

Recently somebody has asked me where the log files are stored. This question is more interesting then it seems. We are using the freely programmable controller UVR16x2 (and its predecessor) UVR1611) ... .. and their Control and Monitoring Interface - CMI: The CMI is a data logger and runs a web server. It logs data … Continue reading Where Are the Files? [Winsol – UVR16x2]

Cloudy Troubleshooting

Actors: Cloud: Service provider delivering an application over the internet. Client: Business using the Cloud Telco: Service provider operating part of the network infrastructure connecting them. elkement: Somebody who always ends up playing intermediary. ~ Client: Cloud logs us off ever so often! We can't work like this! elkement: Cloud, what timeouts do you use? … Continue reading Cloudy Troubleshooting

Logging Fun with UVR16x2: Photovoltaic Generator – Modbus – CAN Bus

The Data Kraken wants to grow new tentacles. I am playing with the CMI - Control and Monitoring Interface - the logger / 'ethernet gateway' connected to our control units (UVR1611, UVR16x2) via CAN bus. The CMI has become a little Data Kraken itself: Inputs and outputs can be created for CAN bus and Modbus, … Continue reading Logging Fun with UVR16x2: Photovoltaic Generator – Modbus – CAN Bus

Let Your Hyperlinks Live Forever!

It is the the duty of a Webmaster to allocate URIs which you will be able to stand by in 2 years, in 20 years, in 200 years. This needs thought, and organization, and commitment. (https://www.w3.org/Provider/Style/URI) Joel Spolsky did it:  I’m bending over backwards not to create “linkrot” — all old links to Joel on Software … Continue reading Let Your Hyperlinks Live Forever!

Reverse Engineering Fun

Recently I read a lot about reverse engineering -  in relation to malware research. I for one simply wanted to get ancient and hardly documented HVAC engineering software to work. The software in question should have shown a photo of the front panel of a device - knobs and displays - augmented with current system's … Continue reading Reverse Engineering Fun

The Orphaned Internet Domain Risk

I have clicked on company websites of social media acquaintances, and something is not right: Slight errors in formatting, encoding errors for special German characters. Then I notice that some of the pages contain links to other websites that advertize products in a spammy way. However, the links to the spammy sites are embedded in … Continue reading The Orphaned Internet Domain Risk