Tag: Forensics

Huntress Capture the Flag – A CTF Marathon

CTF, DFIR, Forensics, Malware, Memory Analysis, OSINT, Steganography

Throughout October, as part of Cyber Security Awareness Month, the team over at Huntress put on a ~30 day Capture the Flag event with 58 unique challenges.

First and foremost, kudos to the organizers for pulling off an event of this size and duration. There were only minor technical difficulties noticed throughout the month, and on more than one occasion those were due to people not observing the rules and using brute force tools where they weren’t needed (or allowed.)

Overall, I found the event to be a great learning experience that challenged me, increased my confidence, and gave me an avenue to pursue skills I want to develop further.

The challenges covered a wide area of subjects with the majority being DFIR related. The categories included:

  • Warm Ups (14)
  • Forensics (10)
  • Malware (16)
  • M365 (4)
  • OSINT (3)
  • Steganography (1)
  • Miscellaneous (10)

Today the final challenge of the event, graced us with another lovely malware sample to analyze.

I was very pleased with myself at having solved nearly 80% of the challenges. There’s still another 20 or so hours to go, so we’ll see if that improves any further. The only categories I didn’t have 100% in were Miscellaneous and Malware. I think this is fair considering my skill levels. The Malware scenarios were appropriately challenging for someone newer to this area. This is an area that I’ve been developing my skills in more recently. I’m looking forward to seeing others’ write-ups on those challenges where I didn’t make it all the way through, and following along with my own data.

Tools used in the CTF

I added a number of new tools to my toolkit throughout the CTF, and got more experienced with some old friends as well. Depending on the challenge I switched between operating systems including MacOS, REMnux (Linux), and a customized Windows VM with a plethora of malware analysis utilities. By the end of the event the tools used included:

  • PowerShell
  • Strings
  • CyberChef
  • Gimp
  • Curl
  • Firepwd.py
  • rita
  • the_silver_searcher
  • nmap
  • dcode.fr
  • meld
  • Cutter
  • Ghidra
  • Python
  • ChatGPT
  • Google Chrome Developer Tools
  • iSteg
  • exiftool
  • Google Lens
  • Google Maps
  • detonaRE
  • Process Monitor (procmon)
  • Visual Studio Code
  • Site Sucker
  • 7zip
  • Magnet AXIOM
  • olevba
  • x64dbg
  • AADInternals
  • Microsoft Excel
  • Event Viewer
  • chainsaw
  • PowerDecode
  • PowerShell ISE
  • rclone
  • Volatility3
  • hashcat
  • impacket

Write-Ups

Over the next few days I’ll be releasing the write-ups on how I solved each of the completed challenges. The organizers requested that no solutions be posted until 24 hours after the conclusion of the CTF.

Based on the amount of content, I’ll be breaking the write-ups down by week number (1-4) and challenge category.

Wednesday:

Thursday:

Friday:

Saturday:

You can follow along through the week, or come back on the weekend to read them all.

Once again, I want to extend my thanks to the Huntress team for a great event. I hope you’ll follow along with my solutions, and please comment with other ways to solve if you have them. It’s all about the learning.

Use the tag #HuntressCTF on BakerStreetForensics.com to see all related posts and solutions for the 2023 Huntress CTF.

Magnet RESPONSE PowerShell

DFIR, Forensic Imaging, PowerShell, Presentations, RAM

I’m excited to share with you a new script I’ve written, Magnet RESPONSE PowerShell.

Magnet RESPONSE is a free tool from Magnet Forensics that makes it easy for investigators as well as non-technical operators to collect triage collections quickly and consistently.

Released initially as a GUI tool for law-enforcement investigators, it’s a single executable that requires no installation. The available command line syntax also makes it very flexible for enterprise use.

So what do I do when there’s a command line interface available, I PowerShell the hell out of it.

If you’ve been following my CyberPipe project, you’ll definitely want to check this one out.

MagnetRESPONSEPowerShell.ps1

Functions:
  • 💻 Capture specified triage artifacts using profiles with Magnet RESPONSE,
  • 🐏 Capture a memory image with DumpIt for Windows or Magnet RAM Capture,
  • 💾 Save all artifacts, output, and audit logs to network drive.
  • 🪟 Supports x86, x64 and ARM64 versions of Windows
Prerequisites:
  • Magnet RESPONSE
  • Web server where you can host MagnetRESPONSE.zip that’s accessible to endpoints.
  • File server repository to save the file collections to.

Please note this is not a Magnet supported product. This script is open source. If you have comments, updates, or suggestions – please do so here or on GitHub via discussion or pull request.

There are two areas of the script for you to customize.

  • The Variable Setup contains the case identification, file server and web server locations.
  • The second section, Collection Profiles, define which artifact groups you want to collect. You can see all the options available in the Magnet RESPONSE CLI Guide.

VARIABLE SETUP

$caseID = "demo-161" # no spaces

$outputpath = "\\Server\Share" # Update to reflect output destination.

$server = "192.168.4.187" # "192.168.1.10" resolves to http://192.168.1.10/MagnetRESPONSE.zip

COLLECTION PROFILES

Within the script we need to have at least one set of collection arguments defined. In this case I’ve built multiple profiles, which are simply un-commented to mark the profile as active. You only want to have one profile enabled at a time. You can design your own collection profiles using any of the available CLI options, just follow the format below.

#### Extended Process Capture

$profileName = "EXTENDED PROCESS CAPTURE"

$arguments = "/capturevolatile /captureextendedprocessinfo /saveprocfiles"

Execution

Once your environment and collection variables are defined, go ahead and run the script on your endpoints. Every host that executes the script will download RESPONSE from the web server, run the specified collection profile, and then save the output to the file server. All data defined in the collection profile will be collected and organized by case name, hostname and timestamp of collection in the central location. The returned files can be examined manually, using open source tools, or products like Magnet AXIOM Cyber.

If you’d like to learn more about the script, and how I integrated it with AXIOM Cyber and Magnet AUTOMATE, you can register for my webcast, Responding at Scale with Magnet RESPONSE. I hope to see you there.

You can download the script at https://github.com/MagnetForensics/Magnet-RESPONSE-PowerShell

Capturing malware evidence with detonaRE

DFIR, Malware, PowerShell, RAM

Lately I’ve been experimenting with a lot of varieties of different malware strains. Each time the malware executes, I have a process where I’ll initiate a packet capture, give the malware some time to spin up, and then execute an evidence capture while the malware is running. Then I’ll revert to a snapshot, make some modifications to the environment, and run the process again.

To make things easier on myself (and to help with late afternoon brain fog) I decided to script out the process with PowerShell.

detonaRE – from Latin, to detonate

  • initiates packet capture
  • launches malware sample
  • terminates packet capture after specified interval
  • initiates evidence collection with Magnet RESPONSE (memory, process, and triage capture)
  • converts collected .etl file (network capture) to .pcap with etl2pcapng.

## variable configuration:
$malwspath = “E:” ## malware source path
$malwdpath = “C:\Users\REM\Desktop\Malware\” ## malware destination path
$malware = “redline-76ca4a.exe” ## malware executable
$pcaptime = 180 ## duration in seconds for pcap capture
$toolsdir = “E:\Tools” ## MagnetRESPONSE.exe and etl2pcapng.exe

In my case I’ve got my malware file on the root of a USB device (E:) that will be attached to the VM. I want to copy the malware to the ‘Malware’ folder on the VM desktop. For this example the malware file is redline-76ca4a.exe. Any tools needed will be stored in E:\Tools.

I’m using the netsh command to capture any network traffic in .etl format. Later on, we’ll convert the .ett to .pcap. This is the same process I utilized in the QuickPcap PowerShell script.

Once the packet capture is running, the malware file gets detonated. The packet capture will continue running for the set duration, the default being 180 seconds or 3 minutes. It’s important not to terminate the packet capture too early. As you can see in the demonstration video below, once this particular malware sample is detonated, it sleeps for a bit and doesn’t show as active on the system until about 45 seconds into the capture.

Once the packet capture is completed, I’m running the command line version of Magnet RESPONSE. If you’re a fan of CyberPipe this is definitely one you’ll want to check out. Using Magnet RESPONSE I collect the memory (Comae DumpIt), pagefile, running processes (full process dumps) and triage system collection. Note, these artifacts can be scaled down by adjusting the Magnet RESPONSE CLI parameters.

Finally, when that’s all done, the .etl file gets converted to .pcap via etl2pcapng.exe. Then I transfer the collected files to my analysis machine and then the real fun begins.

update: (a day later) version 1.1 now also initiates Process Monitor with a filter applied for the malware to be detonated.

Github link for detonaRE

detonaRE v1.0
detonaRE.ps1 v1.1 now includes Process Monitor
detonaRE version 1.2 demo

Upcoming MAGNET Webinar: Magnet2Go

DFIR, DIY, Forensic Imaging, Presentations, RAM, USB

On August 2, join me on behalf of Magnet Forensics, to learn how to build your own ‘Windows to Go’ drive to support offline collections with Magnet OUTRIDER & Magnet ACQUIRE, as well as free tools for live collections like Magnet RESPONSE, Magnet DumpIt, & Magnet RAM Capture. Registration link below.

If you’re looking for the hard drive referrenced in the talk: [amazon] Samsung T7 SSD

Magnet2Go: Building a ‘Windows to Go’ Drive to Support Live and Offline Collections