EXPLORE

Article

PYSA: 2020 to Now

Arete Analysis

Cybersecurity Trends

Cyber Threats

PYSA is the newest variant of the Mespinoza Ransomware as a Service (RaaS) family, which was first observed infecting victims in the wild in December 2019. PYSA is likely a reference to the open-source web application auditing tool PYSA (Protect Your System Amigo) released by security engineers at Facebook.

Like Ryuk, PYSA is dubbed a “big game hunter” for their tendency to target large corporations. Based on their advanced encryption methods, double extortion tactics, and desire to distinguish themselves, this up-and-coming ransomware group is “one to watch.”

Since Q3 2020, Arete has responded to 26 total PYSA cases. With an average ransom payment of $346,603, PYSA ranks third highest in average ransom payouts tracked by Arete through July 2021. Additionally, Arete has observed a steady increase in cases sine Q3 2020 (see Figure 1).

Figure 1: PYSA cases over a one-year period.


Figure 2: Arete PYSA cases average ransom payment.

Targeting Big Game 

PYSA targets large companies or organizations susceptible to extortion, where business downtime would pose a significant impact to operations. By extorting companies with the threat of publishing sensitive data, PYSA increases the chances of ransom payments. The top three sectors targeted by PYSA include K-12 school systems (36%), professional services (20%), and healthcare providers (12%). See Figure 3 for all targeted sectors.

Figure 3: Arete PYSA cases, all targeted sectors.

Sophisticated Criminals 

PYSA exhibits discipline by first surveying compromised systems to determine a victim’s potential “extortion value.” Open-source reporting indicates that PYSA searches not only for common keywords (e.g., PII, balance, routing), but also for keywords (e.g., illegal, fraud, criminal) that could be evidence of illegal activities by the victim.

Arete also identified some other key PYSA activity — specifically, that PYSA occasionally publishes data on leak sites after payment, provides decryptors that partially corrupt data, and stops communication for multiple days during negotiations.

Figure 4: Average time of business interruption.

Infection vector and persistence: Human-operated ransomware

Arete identified the following PYSA tactics, techniques, and procedures (TTPs) as being consistent with manually operated ransomware during the initial access phase:

  • Uses brute force remote desktop protocol (RDP) attacks against central management consoles, domain controllers, and Active Directory accounts.

  • Exfiltrates password databases prior to exploitation.

  • Leverages Mimikatz in victim environments, likely to gain access to credentials.

Additionally, Arete observed the following persistence toolset as part of PYSA campaigns:

  • Gasket. A backdoor written in the Go programming language, Gasket is designed as a backup to RDP to maintain access to the network. Gasket has many capabilities (e.g., “MagicSocks”) that allow PYSA to tunnel traffic to an externally controlled server.

Figure 5: Gasket functionality.

  • MagicSocks. Leverages code from the Chisel project to tunnel traffic from the local system to an external, actor-controlled server. Next, uses Chisel code to tunnel traffic out of the local system to a landing page (“creatordampfe[.]xyz”) before routing the traffic to an unknown actor-controlled server.

Advanced encryption techniques

According to open-source data, PYSA uses Crypto++ to encrypt victim files with both RSA-4096 and AES-256-CFB. The group appends the encrypted files with the “.pysa” extension and leverages an allowlist and denylist to determine which files to encrypt.

  • The denylist contains all files to be encrypted.

  • The allowlist includes vital directories, such as Windows and Boot, which, if encrypted, would make recovery via the decryptor impossible. After, PYSA drops the ransom note (Figure 6) in every directory listed in the denylist.

Figure 6: PYSA ransom note.

PYSA threat likely to remain steady 

PYSA utilized the rapid shift of corporations to remote work during COVID-19 for opportunistic targeting against RDP and remote admin infrastructure. Arete asserts that the threat posed by PYSA campaigns will likely remain steady, with PYSA targeting larger corporations across sectors to demand higher ransom payments. PYSA’s discipline, target selection, and advanced encryption techniques make them a credible threat on the ransomware scene.

How Arete can help you “Protect Your Systems Amigo”

Arete has a complete suite of managed security services, including managed detection and response (MDR), SentinelOne Endpoint Detection and Response (EDR) software deployment, and Arsinal threat hunting services for defending against ransomware attacks.

The following rulesets would detect PYSA activity on a client endpoint:

  • PowerShell used to disable Windows Defender Protection.

  • Lsass dump.

  • Firewall Exception for Remote Desktop.

  • MS Windows Defender stopped.

  • Security Tool Services stopped.

  • Volume Shadow Copy deletion.

  • Process Masquerading in Registry – Svchost.

  • Advanced Port Scanner Tool download.

  • Advanced Port Scanner Process Masquerading.

  • Advanced Port Scanner Process.

  • Advanced Port Scanner File detected.

  • Mimikatz Process Execution.

  • Advanced IP Scanner Network Mapping Tool download.

  • Advanced IP Scanner Network Mapping Tool Process.

  • Advanced IP Scanner Network Mapping File detected.

  • Advanced IP Scanner Process Masquerading.

Indicators

Ransom Note Emails

  • johnfitzgerald@onionmail.org

  • cristianpalmerss@protonmail.com

  • wcraijones@protonmail.com

  • dec_restore1@outlook.com

  • zljanczplaizr@onionmail.org

  • EfreTavernia@protonmail.com

  • lizawilkinson@onionmail.org

  • Makailahuff@protonmail.com

  • Davionfinley@protonmail.com

  • joedansereau@onionmail.org

  • m0arc7bdhsohar@onionmail.org

  • david_ansty@protonmail.com

  • t.trstram@protonmail.com

Resources

Back to Blog Posts

Article

Attack Patterns in Settra Incidents

Recent Settra ransomware incidents demonstrate a consistent operational pattern involving compromised credentials, VPN access, and the deployment of ransomware executables tailored to victim environments. Researchers have observed Settra naming ransomware executables after the targeted organization's domain while following similar attack sequences across multiple intrusions. Arete has also identified overlapping tactics, techniques, and tools in Settra engagements observed from June to August, including the use of MeshAgent for remote access and Bring Your Own Vulnerable Driver (BYOVD) techniques to weaken endpoint security controls. 

What’s Notable and Unique 

  • Settra operators have been observed naming ransomware executables after the victim organization's domain, creating a direct association between the payload and the targeted environment.

  • Initial access vectors have included targeting exposed VPN infrastructure and the use of compromised credentials, reducing the need for traditional exploitation of vulnerabilities.

  • Arete observed MeshAgent in multiple Settra engagements, which provides threat actors with a mechanism for remote access and continued activity within compromised environments.

  • Settra engagements have also included Bring Your Own Vulnerable Driver (BYOVD) activity, which can be used to bypass or impair security controls by abusing legitimate but vulnerable drivers.

Analyst Comments

Recent Settra activity demonstrates how ransomware operators can combine credential-based access, remote management tooling, and security control evasion techniques to establish and maintain access before ransomware deployment. The repeated use of similar tools and operational patterns across incidents provides useful detection opportunities for defenders. Organizations should closely monitor VPN authentication activity, unusual use of compromised credentials, unexpected MeshAgent deployment, ransomware executables with victim-specific naming conventions, and suspicious driver activity associated with attempts to disable or bypass endpoint security controls.

Arete’s MDR practice detects Settra’s full attack chain, with special attention to the staging of BYOVD activity for defense evasion. However, for us to detect it, SentinelOne needs to be fully deployed across an environment. To support organizations with full deployment, Arete offers SentinelOne Deployment Assistance. This service is designed to ensure that SentinelOne is deployed across all eligible endpoints, eliminating coverage gaps that could otherwise expose the organization to ransomware, malware, credential theft, and other advanced threats. Through endpoint discovery, inventory reconciliation, and deployment assistance, Arete helps organizations achieve comprehensive protection and maximize the effectiveness of their SentinelOne investment. Contact clientcares@areteir.com to learn more.

Sources

  • Ready, Settra, Go: New Settra Ransomware Variant Deploys MeshAgent RMM

Article

AI Agents Used in Campaign Against PaperCut

In late August, a threat actor used hundreds of AI agents to develop and launch a global exploitation campaign targeting vulnerable PaperCut NG and MF servers. PaperCut is print management software, and researchers determined that the operation compromised at least 440 PaperCut instances linked to 395 distinct organizations across 48 countries. The AI agents were tasked with building, testing, and refining exploits for CVE-2026-81578 and CVE-2026-82078 both security flaws affecting PaperCut software and flagged as actively exploited earlier this month.  It is currently unclear if the threat actor is solely focused on access development to be handed off to other affiliated actors, or if they will directly leverage their access to achieve follow-on objectives such as data theft or ransomware deployment.

What’s Notable and Unique

  • Researchers observed three attack paths following the exploitation of vulnerable PaperCut servers. Threat actors would harvest credentials from LSASS memory and registry secrets to perform pass-the-hash attacks, leverage older unpatched Windows vulnerabilities (CVE-2021-42278 and CVE-2021-42287) to escalate privileges in unpatched environments, or, in some cases, directly add newly created accounts to the Domain Admins group when PaperCut was running with domain-level privileges.


  • Upon achieving remote code execution and credential harvesting within a self-hosted lab environment, the threat actor deployed hundreds of AI-powered agents that leveraged OpenAI Codex, DeepSeek models, and publicly available offensive security tools, including Mimikatz, SharpHound, Certipy, Rubeus, and Impacket, to automate reconnaissance, exploitation, and post-compromise activities. The attackers subsequently used a DCSync attack to obtain a database dump containing domain credentials. 

Analyst Comments

The observed activity demonstrates how threat actors are increasingly leveraging AI and large language models (LLMs) to accelerate cyber operations at unprecedented speed and scale. In this campaign, the adversary progressed from exploit development to remote code execution within hours and, in some cases, achieved Domain Administrator privileges in as little as five minutes. The AI-assisted workflow enabled rapid reconnaissance, exploitation, credential theft, privilege escalation, and lateral movement, allowing the compromise of multiple organizations within seconds. This activity highlights the growing threat posed by AI-enabled adversaries capable of conducting large-scale intrusions with greater efficiency and operational velocity. Organizations affected by the PaperCut vulnerabilities are strongly advised to apply the latest security updates and implement the vendor's recommended mitigation measures to reduce the risk of compromise and unauthorized access. 

Sources

  • Agents Gone Wild: An AI-Orchestrated Global Campaign Against PaperCut NG/MF 

  • AI-powered attack exploited PaperCut flaws to hack 395 organizations 

  • PaperCut Attacker Uses Hundreds of AI Agents to Compromise 440+ Instances 

Article

Adversarial AI Evolves from Prompting to Autonomous Attack Workflows

Cybercriminals and state-linked threat actors are increasingly incorporating artificial intelligence (AI) into multiple stages of offensive operations. Rather than relying on AI only for content generation or research, threat actors are now consistently using it to support reconnaissance, vulnerability discovery, credential theft, malware development, social engineering, and activities following initial compromise. The growing use of automated and agent-based workflows is allowing adversaries to coordinate offensive malicious activities with less manual involvement, potentially increasing the speed, scale, and efficiency of future campaigns.

What’s Notable and Unique

  •  In one observed campaign, threat actors used AI to plan, build, and conduct an automated credential-harvesting operation within just several hours, demonstrating how compromised infrastructure can be rapidly repurposed to support larger-scale malicious activity.

  • Arete has observed several threat groups using AI-assisted capabilities to facilitate the analysis of data obtained during exfiltration so far this year, including INC Ransom, FulcrumSec, and Settra.

  • Attackers are also attempting to reproduce proprietary AI capabilities. Large-scale automated prompting campaigns have been used to extract information about the behavior and capabilities of proprietary AI models. The use of numerous accounts and intermediary infrastructure can make these activities more difficult to identify and attribute.

Analyst Comments

AI is increasingly becoming an operational component in the threat landscape rather than simply a tool that improves attacker productivity. By connecting reconnaissance, development, credential operations, and other activities through automated workflows, threat actors can conduct campaigns more quickly and reduce reliance on continuous human input. This trend also impacts security requirements for organizations deploying AI technologies. AI models, development environments, cloud resources, identities, repositories, and automated workflows should increasingly be considered interconnected elements of the enterprise attack surface, and organizations should maintain visibility across these areas and ensure that security controls account for both conventional threats and AI-enabled attack techniques.

Sources

  • GTIG AI Threat Tracker: From Prompting to Autonomy – The Evolution of Adversarial AI

Article

Top 9 Security Controls for SMBs

In today’s complex cyber threat landscape, small and medium-sized businesses (SMBs) should implement a layered, multi-pronged approach to security. Here are some proven, effective controls to consider:

1.        Implement MFA for All Users
Multi-factor authentication (MFA) is an effective and accessible way to protect sensitive data, comply with regulatory standards, and prevent unauthorized access to critical systems. By ensuring that users not only use a password but also a secure token, an organization can significantly reduce phishing attempts, credential stuffing attacks, and ransomware incidents. MFA should be enabled for email, VPN, and critical system access.

2.        Update Patch Management Programs
A modern patching program should include policies and mechanisms to manage software updates in a timely manner. Patching efforts should address not just operating system updates, but also commonly utilized software within the environment. An active patching plan aims to reduce the mean time to patch and provide metrics on existing patch efforts. In the event of a high-severity vulnerability, a mature patching program should also be able to identify the risks and exposure for a given set of systems based on the average time to patch. This helps stakeholders make informed decisions when a new exploit is released.

3.        Leverage a Properly Managed Endpoint Detection and Response (EDR) Tool
With real-time threat detection and advanced visibility, endpoint detection and response (EDR) solutions can enhance an organization’s ability to detect and investigate potential malicious activity, including ransomware, lateral movement, fileless attacks, and more. Effective management of EDR should include proper configuration, regular agent updates, and established procedures for responding to alerts.

4.        Enhance EDR with Frontline Incident Intelligence
While EDR solutions are an important component of a security program, threat actors are continually adapting their techniques to evade detection, and as a result, standard detection methods may not always identify emerging threats or novel attack behaviors. To strengthen protection, organizations can supplement EDR tools with custom detection rules informed by incident response data. These rules can help identify indicators of compromise observed during cyber incidents, providing an additional layer of visibility beyond traditional detections.

Arete Bloktd℠ illustrates this approach by transforming threat intelligence and malware analysis into curated detection rules for EDR tools. Applying frontline intelligence to security tools can result in earlier detection, less investigative burden, and a more confident response. 

5.        Create and Continuously Test an Incident Response (IR) Plan
An incident response plan can help an organization effectively identify, respond to, and recover from a cybersecurity incident while minimizing disruption and downtime. An IR plan defines clear roles, escalation paths, communication strategies, and decision frameworks for both internal and external teams. To be effective, these plans should be regularly tested with post-incident reviews or tabletop exercises involving key stakeholders.

6.        Maintain Encrypted and Tested Data Backups
In the case of a cyberattack, backups can help organizations maintain business continuity, support ransom negotiations with threat actors, and contribute to a timely and successful recovery. Encrypting backups makes it more difficult for threat actors to access or alter them, and regular testing ensures they remain accessible during a security incident.

7.        Conduct Employee Security Awareness Training
Human error is a leading cause of cybersecurity incidents, and an organization’s employees are its first line of defense against cyber threats. Security awareness training reinforces the importance of data confidentiality, supports regulatory compliance, and helps employees recognize and understand red flags such as suspicious emails, malicious links, and social engineering attempts.

8.        Assess and Address Existing Risk and Vulnerabilities
To maintain a proactive approach to risk management and improve resilience, organizations should regularly assess existing vulnerabilities through expert-led Vulnerability Assessments, Penetration Testing, and Threat Hunting Assessments. These exercises can help identify security gaps, support regulatory compliance, and prevent potential incidents. During remediation, prioritize high-impact vulnerabilities and make a plan for periodic assessments.

9.        Apply Least-Privilege Access Controls
Employees should have access only to the systems, applications, and data necessary to perform their jobs. By removing unnecessary administrative privileges and regularly reviewing user permissions, organizations can reduce the risk of unauthorized access and limit the damage caused by compromised accounts or insider threats.

Organizations should regularly review their cybersecurity programs, stay informed about emerging threats, and evaluate whether their security controls are adapting to the evolving threat landscape.