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Living off the Land : Comment les pirates informatiques se fondent dans votre environnement







What is Living off the Land attack?
Living off the Land is a strategy which involves threat actors leveraging the utilities readily available within the target organization’s digital environment to move through the cyber kill chain. This is a popular method because It is often cheaper, easier, and more effective to make use of an organization’s own infrastructure in an attempt to attack rather than writing bespoke malware for every heist.
While the term was first coined in 2013, Living off the Land tools, techniques, and procedures (TTPs) have boomed in popularity in recent years. In part, this is because the traditional approach of defensive security — blocklisting file hashes, domains, and other traces of threats encountered in previous attacks — is ill-equipped to identify these attacks. So these stealthy, often fileless attacks, have pushed their way into the mainstream.
How does Living off the Land attack work?
Living off the Land attacks have a particular history in highly organized, targeted hacking. APT groups have long favored Living off the Land TTPs, since evasion is a top priority. And trends show that ransomware groups are opting for human-operated ransomware that relies heavily on Living off the Land techniques, instead of commodity malware.
Among some of the most commonly used tools exploited for nefarious purposes are Powershell, Windows Management Interface (WMI), and PsExec. These tools are regularly used by network administrators as part of their daily routines, and traditional security tools reliant on static rules and signatures often have a hard time distinguishing between legitimate and malicious use.
Hallmarks of a Living off the Land attack
Before a threat actor turns your infrastructure against you in a Living off the Land attack, they must be able to execute commands on a targeted system. Therefore, Living off the Land attacks are a post-infection framework for network reconnaissance, lateral movement, and persistence.
Once a device is infected, there are hundreds of system tools at the attacker’s disposal – these may be pre-installed on the system or downloaded via Microsoft-signed binaries. And, in the wrong hands, other trusted third-party administration tools on the network can also turn from friend to foe.
As Living off the Land techniques evolve, a single typical attack is hard to determine. However, we can group these TTPs in broader categories.
Microsoft-signed Living off the Land TTPs
Microsoft is ubiquitous in the business world and across industries. The Living off the Land Binaries and Scripts (LOLBAS) project aims to document all Microsoft-signed binaries and scripts that include functionality for APT groups in Living off the Land attacks. To date, there are 135 system tools on this list that are vulnerable to misuse, each aiding a different objective. These could be the creation of new user accounts, data compression and exfiltration, system information gathering, launching processes on a target destination or even the disablement of security services. Both Microsoft’s documentation of vulnerable pre-installed tools and the LOLBAS project are growing, non-exhaustive lists.
Command line
When it comes to delivering a malicious payload to the target, WMI (WMIC.exe), the command line tool (cmd.exe), and PowerShell (powershell.exe) were used most frequently by attackers, according to a recent study. These commonly exploited command line utilities are used during the configuration of security settings and system properties, provide sensitive network or device status updates, and facilitate the transfer and execution of files between devices.
Specifically, the command line group shares three key traits:
- They are readily available on Windows systems.
- They are frequently used by most administrators or internal processes to perform everyday tasks.
- They can perform their core functionalities without writing data to a disk.
Mimikatz
Mimikatz differs from other tools in that it is not pre-installed on most systems. It is an open-source utility used for the dumping of passwords, hashes, PINs and Kerberos tickets. While some network administrators may use Mimikatz to perform internal vulnerability assessments, it is not readily available on Windows systems.
Traditional security approaches used to detect the download, installation, and use of Mimikatz are often insufficient. There exists a wide range of verified and well documented techniques for obfuscating tooling like Mimikatz, meaning even an unsophisticated attacker can subvert basic string or hash-based detections.
Self-Learning AI fights Living off the Land attacks
Living off the Land techniques have proven incredibly effective at enabling attackers to blend into organizations’ digital environments. It is normal for millions of credentials, network tools, and processes to be logged each day across a single digital ecosystem. So how can defenders spot malicious use of legitimate tools amidst this digital noise?
As with most threats, basic network hygiene is the first step. This includes implementing the principle of least privilege, de-activating all unnecessary programs, setting up software whitelisting, and performing asset and application inventory checks. However, while these measures are a step in the right direction, with enough time a sophisticated attacker will always manage to work their way around them.
Self-Learning AI technology has become fundamental in shining a light on attackers using an organization’s own infrastructure against them. It learns any given unique digital environment from the ground up, understanding the ‘pattern of life’ for every device and user. Living off the Land attacks are therefore identified in real time from a series of subtle deviations. This might include a new credential or unusual SMB / DCE-RPC usage.
Its deep understanding of the business enables it to spot attacks that fly under the radar of other tools. With a Living off the Land attack, the AI will recognize that although usage of particular tool might be normal for an organization, the way in which that tool is used allows the AI to reveal seemingly benign behavior as unmistakably malicious.
For example, Self-Learning AI might observe the frequent usage of Powershell user-agents across multiple devices, but will only report an incident if the user agent is observed on a device at an unusual time.
Similarly, Darktrace might observe WMI commands being sent between thousands of combinations of devices each day, but will only alert on such activity if the commands are uncommon for both the source and the destination.
And even the subtle indicators of Mimikatz exploitation, like new credential usage or uncommon SMB traffic, will not be buried among the normal operations of the infrastructure.
Living off the Land techniques aren’t going away any time soon. Recognizing this, security teams are beginning to move away from ‘legacy’-based defenses that rely on historical attack data to catch the next attack, and towards AI that uses a bespoke and evolving understanding of its surroundings to detect subtle deviations indicative of a threat – even if that threat makes use of legitimate tools.
Thanks to Darktrace analysts Isabel Finn and Paul Jennings for their insights on the above threat find and supporting MITRE ATT&CK mapping.
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The Implications of NIS2 on Cyber Security and AI



The NIS2 Directive requires member states to adopt laws that will improve the cyber resilience of organizations within the EU. It impacts organizations that are “operators of essential services”. Under NIS 1, EU member states could choose what this meant. In an effort to ensure more consistent application, NIS2 has set out its own definition. It eliminates the distinction between operators of essential services and digital service providers from NIS1, instead defining a new list of sectors:
- Energy (electricity, district heating and cooling, gas, oil, hydrogen)
- Transport (air, rail, water, road)
- Banking (credit institutions)
- Financial market infrastructures
- Health (healthcare providers and pharma companies)
- Drinking water (suppliers and distributors)
- Digital infrastructure (DNS, TLD registries, telcos, data center providers, etc.)
- ICT service providers (B2B): MSSPs and managed service providers
- Public administration (central and regional government institutions, as defined per member state)
- Space
- Postal and courier services
- Waste management
- Chemicals
- Food
- Manufacturing of medical devices
- Computers and electronics
- Machinery and equipment
- Motor vehicles, trailers and semi-trailers and other transport equipment
- Digital providers (online market places, online search engines, and social networking service platforms) and research organizations.
With these updates, it becomes harder to try and find industry segments not included within the scope. NIS2 represents legally binding cyber security requirements for a significant region and economy. Standout features that have garnered the most attention include the tight timelines associated with notification requirements. Under NIS 2, in-scope entities must submit an initial report or “early warning” to the competent national authority or computer security incident response team (CSIRT) within 24 hours from when the entity became aware of a significant incident. This is a new development from the first iteration of the Directive, which used more vague language of the need to notify authorities “without undue delay”.
Another aspect gaining attention is oversight and regulation – regulators are going to be empowered with significant investigation and supervision powers including on-site inspections. We cover more on this in our white paper.
The stakes are now higher, with the prospect of fines that are capped at €10 million or 2% of an offending organization’s annual worldwide turnover – whichever is greater. Added to that, the NIS2 Directive includes an explicit obligation to hold members of management bodies personally responsible for breaches of their duties to ensure compliance with NIS2 obligations – and members can be held personally liable.
The risk management measures introduced in the Directive are not altogether surprising – they reflect common best practices. Many organizations (especially those that are newly in scope for NIS2) may have to expand their cyber security capabilities, but there’s nothing controversial or alarming in the required measures. For organizations in this situation, there are various tools, best practices, and frameworks they can leverage. Darktrace in particular provides capabilities in the areas of visibility, incident handling, and reporting that can help.
NIS2 and Cyber AI
The use of AI is not an outright requirement within NIS2 – which may be down to lack of knowledge and expertise in the area, and/or the immaturity of the sector. The clue to this might be in the timing: the provisional agreement on the NIS2 text was reached in May 2022 – six months before ChatGPT and other open-source Generative AI tools propelled broader AI technology into the forefront of public consciousness. If the language were drafted today, it's not far-fetched to imagine AI being mentioned much more prominently and perhaps even becoming a requirement.
NIS2 does, however, very clearly recommend that “member states should encourage the use of any innovative technology, including artificial intelligence”[1]. Another section speaks directly to essential and important entities, saying that they should “evaluate their own cyber security capabilities, and where appropriate, pursue the integration of cyber security enhancing technologies, such as artificial intelligence or machine learning systems…”[2]
One of the recitals states that “member states should adopt policies on the promotion of active cyber protection”. Where active cyber protection is defined as “the prevention, detection, monitoring, analysis and mitigation of network security breaches in an active manner.”[3]
From a Darktrace perspective, our self-learning Cyber AI technology is precisely what enables our technology to deliver active cyber protection – protecting organizations and uplifting security teams at every stage of an incident lifecycle – from proactively hardening defenses before an attack is launched, to real-time threat detection and response, through to recovering quickly back to a state of good health.
The visibility provided by Darktrace is vital to understanding the effectiveness of policies and ensuring policy compliance. NIS2 also covers incident handling and business continuity, which Darktrace HEAL addresses through AI-enabled incident response, readiness reports, simulations, and secure collaborations.
Reporting is integral to NIS2 and organizations can leverage Darktrace’s incident reporting features to present the necessary technical details of an incident and provide a jump start to compiling a full report with business context and impact.
What’s Next for NIS2
We don’t yet know the details for how EU member states will transpose NIS2 into national law – they have until 17th October 2024 to work this out. The Commission also commits to reviewing the functioning of the Directive every three years. Given how much our overall understanding and appreciation for not only the dangers of AI but also its power (perhaps even necessity in the realm of cyber security) is changing, we may see many member states will leverage the recitals’ references to AI in order to make a strong push if not a requirement that essential and important organizations within their jurisdiction leverage AI.
Organizations are starting to prepare now to meet the forthcoming legislation related to NIS2. To see how Darktrace can help, talk to your representative or contact us.
[1] (51) on page 11
[2] (89) on page 17
[3] (57) on page 12

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A l'intérieur du SOC
PurpleFox in a Henhouse: How Darktrace Hunted Down a Persistent and Dynamic Rootkit



Versatile Malware: PurpleFox
As organizations and security teams across the world move to bolster their digital defenses against cyber threats, threats actors, in turn, are forced to adopt more sophisticated tactics, techniques and procedures (TTPs) to circumvent them. Rather than being static and predictable, malware strains are becoming increasingly versatile and therefore elusive to traditional security tools.
One such example is PurpleFox. First observed in 2018, PurpleFox is a combined fileless rootkit and backdoor trojan known to target Windows machines. PurpleFox is known for consistently adapting its functionalities over time, utilizing different infection vectors including known vulnerabilities (CVEs), fake Telegram installers, and phishing. It is also leveraged by other campaigns to deliver ransomware tools, spyware, and cryptocurrency mining malware. It is also widely known for using Microsoft Software Installer (MSI) files masquerading as other file types.
The Evolution of PurpleFox
The Original Strain
First reported in March 2018, PurpleFox was identified to be a trojan that drops itself onto Windows machines using an MSI installation package that alters registry values to replace a legitimate Windows system file [1]. The initial stage of infection relied on the third-party toolkit RIG Exploit Kit (EK). RIG EK is hosted on compromised or malicious websites and is dropped onto the unsuspecting system when they visit browse that site. The built-in Windows installer (MSIEXEC) is leveraged to run the installation package retrieved from the website. This, in turn, drops two files into the Windows directory – namely a malicious dynamic-link library (DLL) that acts as a loader, and the payload of the malware. After infection, PurpleFox is often used to retrieve and deploy other types of malware.
Subsequent Variants
Since its initial discovery, PurpleFox has also been observed leveraging PowerShell to enable fileless infection and additional privilege escalation vulnerabilities to increase the likelihood of successful infection [2]. The PowerShell script had also been reported to be masquerading as a .jpg image file. PowerSploit modules are utilized to gain elevated privileges if the current user lacks administrator privileges. Once obtained, the script proceeds to retrieve and execute a malicious MSI package, also masquerading as an image file. As of 2020, PurpleFox no longer relied on the RIG EK for its delivery phase, instead spreading via the exploitation of the SMB protocol [3]. The malware would leverage the compromised systems as hosts for the PurpleFox payloads to facilitate its spread to other systems. This mode of infection can occur without any user action, akin to a worm.
The current iteration of PurpleFox reportedly uses brute-forcing of vulnerable services, such as SMB, to facilitate its spread over the network and escalate privileges. By scanning internet-facing Windows computers, PurpleFox exploits weak passwords for Windows user accounts through SMB, including administrative credentials to facilitate further privilege escalation.
Darktrace detection of PurpleFox
In July 2023, Darktrace observed an example of a PurpleFox infection on the network of a customer in the healthcare sector. This observation was a slightly different method of downloading the PurpleFox payload. An affected device was observed initiating a series of service control requests using DCE-RPC, instructing the device to make connections to a host of servers to download a malicious .PNG file, later confirmed to be the PurpleFox rootkit. The device was then observed carrying out worm-like activity to other external internet-facing servers, as well as scanning related subnets.
Darktrace DETECT™ was able to successfully identify and track this compromise across the cyber kill chain and ensure the customer was able to take swift remedial action to prevent the attack from escalating further.
While the customer in question did have Darktrace RESPOND™, it was configured in human confirmation mode, meaning any mitigative actions had to be manually applied by the customer’s security team. If RESPOND had been enabled in autonomous response mode at the time of the attack, it would have been able to take swift action against the compromise to contain it at the earliest instance.
Attack Overview

Initial Scanning over SMB
On July 14, 2023, Darktrace detected the affected device scanning other internal devices on the customer’s network via port 445. The numerous connections were consistent with the aforementioned worm-like activity that has been reported from PurpleFox behavior as it appears to be targeting SMB services looking for open or vulnerable channels to exploit.
This initial scanning activity was detected by Darktrace DETECT, specifically through the model breach ‘Device / Suspicious SMB Scanning Activity’. Darktrace’s Cyber AI Analyst™ then launched an autonomous investigation into these internal connections and tied them into one larger-scale network reconnaissance incident, rather than a series of isolated connections.

As Darktrace RESPOND was configured in human confirmation mode, it was unable to autonomously block these internal connections. However, it did suggest blocking connections on port 445, which could have been manually applied by the customer’s security team.

Privilege Escalation
The device successfully logged in via NTLM with the credential, ‘administrator’. Darktrace recognized that the endpoint was external to the customer’s environment, indicating that the affected device was now being used to propagate the malware to other networks. Considering the lack of observed brute-force activity up to this point, the credentials for ‘administrator’ had likely been compromised prior to Darktrace’s deployment on the network, or outside of Darktrace’s purview via a phishing attack.
Exploitation
Darktrace then detected a series of service control requests over DCE-RPC using the credential ‘admin’ to make SVCCTL Create Service W Requests. A script was then observed where the controlled device is instructed to launch mshta.exe, a Windows-native binary designed to execute Microsoft HTML Application (HTA) files. This enables the execution of arbitrary script code, VBScript in this case.


There are a few MSIEXEC flags to note:
- /i : installs or configures a product
- /Q : sets the user interface level. In this case, it is set to ‘No UI’, which is used for “quiet” execution, so no user interaction is required
Evidently, this was an attempt to evade detection by endpoint users as it is surreptitiously installed onto the system. This corresponds to the download of the rootkit that has previously been associated with PurpleFox. At this stage, the infected device continues to be leveraged as an attack device and scans SMB services over external endpoints. The device also appeared to attempt brute-forcing over NTLM using the same ‘administrator’ credential to these endpoints. This activity was identified by Darktrace DETECT which, if enabled in autonomous response mode would have instantly blocked similar outbound connections, thus preventing the spread of PurpleFox.

Installation
On August 9, Darktrace observed the device making initial attempts to download a malicious .PNG file. This was a notable change in tactics from previously reported PurpleFox campaigns which had been observed utilizing .MOE files for their payloads [3]. The .MOE payloads are binary files that are more easily detected and blocked by traditional signatured-based security measures as they are not associated with known software. The ubiquity of .PNG files, especially on the web, make identifying and blacklisting the files significantly more difficult.
The first connection was made with the URI ‘/test.png’. It was noted that the HTTP method here was HEAD, a method similar to GET requests except the server must not return a message-body in the response.
The metainformation contained in the HTTP headers in response to a HEAD request should be identical to the information sent in response to a GET request. This method is often used to test hypertext links for validity and recent modification. This is likely a way of checking if the server hosting the payload is still active. Avoiding connections that could possibly be detected by antivirus solutions can help keep this activity under-the-radar.


The server responds with a status code of 200 before the download begins. The HEAD request could be part of the attacker’s verification that the server is still running, and that the payload is available for download. The ‘/test.png’ HEAD request was sent twice, likely for double confirmation to begin the file transfer.

Subsequent analysis using a Packet Capture (PCAP) tool revealed that this connection used the Windows Installer user agent that has previously been associated with PurpleFox. The device then began to download a payload that was masquerading as a Microsoft Word document. The device was thus able to download the payload twice, from two separate endpoints.
By masquerading as a Microsoft Word file, the threat actor was likely attempting to evade the detection of the endpoint user and traditional security tools by passing off as an innocuous text document. Likewise, using a Windows Installer user agent would enable threat actors to bypass antivirus measures and disguise the malicious installation as legitimate download activity.
Darktrace DETECT identified that these were masqueraded file downloads by correctly identifying the mismatch between the file extension and the true file type. Subsequently, AI Analyst was able to correctly identify the file type and deduced that this download was indicative of the device having been compromised.
In this case, the device attempted to download the payload from several different endpoints, many of which had low antivirus detection rates or open-source intelligence (OSINT) flags, highlighting the need to move beyond traditional signature-base detections.



If Darktrace RESPOND was enabled in autonomous response mode at the time of the attack it would have acted by blocking connections to these suspicious endpoints, thus preventing the download of malicious files. However, as RESPOND was in human confirmation mode, RESPOND actions required manual application by the customer’s security team which unfortunately did not happen, as such the device was able to download the payloads.
Conclusion
The PurpleFox malware is a particularly dynamic strain known to continually evolve over time, utilizing a blend of old and new approaches to achieve its goals which is likely to muddy expectations on its behavior. By frequently employing new methods of attack, malicious actors are able to bypass traditional security tools that rely on signature-based detections and static lists of indicators of compromise (IoCs), necessitating a more sophisticated approach to threat detection.
Darktrace DETECT’s Self-Learning AI enables it to confront adaptable and elusive threats like PurpleFox. By learning and understanding customer networks, it is able to discern normal network behavior and patterns of life, distinguishing expected activity from potential deviations. This anomaly-based approach to threat detection allows Darktrace to detect cyber threats as soon as they emerge.
By combining DETECT with the autonomous response capabilities of RESPOND, Darktrace customers are able to effectively safeguard their digital environments and ensure that emerging threats can be identified and shut down at the earliest stage of the kill chain, regardless of the tactics employed by would-be attackers.
Credit to Piramol Krishnan, Cyber Analyst, Qing Hong Kwa, Senior Cyber Analyst & Deputy Team Lead, Singapore
Appendices
Darktrace Model Detections
- Device / Increased External Connectivity
- Device / Large Number of Connections to New Endpoints
- Device / SMB Session Brute Force (Admin)
- Compliance / External Windows Communications
- Anomalous Connection / New or Uncommon Service Control
- Compromise / Unusual SVCCTL Activity
- Compromise / Rare Domain Pointing to Internal IP
- Anomalous File / Masqueraded File Transfer
RESPOND Models
- Antigena / Network / Significant Anomaly / Antigena Breaches Over Time Block
- Antigena / Network / External Threat / Antigena Suspicious Activity Block
- Antigena / Network / Significant Anomaly / Antigena Significant Anomaly from Client Block
- Antigena / Network / Significant Anomaly / Antigena Enhanced Monitoring from Client Block
- Antigena / Network / External Threat / Antigena Suspicious File Block
- Antigena / Network / External Threat / Antigena File then New Outbound Block
List of IoCs
IoC - Type - Description
/C558B828.Png - URI - URI for Purple Fox Rootkit [4]
5b1de649f2bc4eb08f1d83f7ea052de5b8fe141f - File Hash - SHA1 hash of C558B828.Png file (Malware payload)
190.4.210[.]242 - IP - Purple Fox C2 Servers
218.4.170[.]236 - IP - IP for download of .PNG file (Malware payload)
180.169.1[.]220 - IP - IP for download of .PNG file (Malware payload)
103.94.108[.]114:10837 - IP - IP from Service Control MSIEXEC script to download PNG file (Malware payload)
221.199.171[.]174:16543 - IP - IP from Service Control MSIEXEC script to download PNG file (Malware payload)
61.222.155[.]49:14098 - IP - IP from Service Control MSIEXEC script to download PNG file (Malware payload)
178.128.103[.]246:17880 - IP - IP from Service Control MSIEXEC script to download PNG file (Malware payload)
222.134.99[.]132:12539 - IP - IP from Service Control MSIEXEC script to download PNG file (Malware payload)
164.90.152[.]252:18075 - IP - IP from Service Control MSIEXEC script to download PNG file (Malware payload)
198.199.80[.]121:11490 - IP - IP from Service Control MSIEXEC script to download PNG file (Malware payload)
MITRE ATT&CK Mapping
Tactic - Technique
Reconnaissance - Active Scanning T1595, Active Scanning: Scanning IP Blocks T1595.001, Active Scanning: Vulnerability Scanning T1595.002
Resource Development - Obtain Capabilities: Malware T1588.001
Initial Access, Defense Evasion, Persistence, Privilege Escalation - Valid Accounts: Default Accounts T1078.001
Initial Access - Drive-by Compromise T1189
Defense Evasion - Masquerading T1036
Credential Access - Brute Force T1110
Discovery - Network Service Discovery T1046
Command and Control - Proxy: External Proxy T1090.002
References
- https://blog.360totalsecurity.com/en/purple-fox-trojan-burst-out-globally-and-infected-more-than-30000-users/
- https://www.trendmicro.com/en_us/research/19/i/purple-fox-fileless-malware-with-rookit-component-delivered-by-rig-exploit-kit-now-abuses-powershell.html
- https://www.akamai.com/blog/security/purple-fox-rootkit-now-propagates-as-a-worm
- https://www.foregenix.com/blog/an-overview-on-purple-fox
- https://www.trendmicro.com/en_sg/research/21/j/purplefox-adds-new-backdoor-that-uses-websockets.html