Article

Ransomware Decryptors for a (varying) fee

Dec 24, 2020

Arete Analysis

Red digital warning symbol glowing on a circuit board interface, representing active ransomware exploitation of the VMware ESXi CVE 2025 22225 vulnerability and hypervisor compromise.

Ransomware attacks wreak havoc on business operations. Destroying recovery options, instilling fear and panic, and most often creating high levels of stress for IT staff, owners, and operators. A simple, but often costly fix is to just pay the Threat Actor for the decryption utility. While making a payment to an anonymous entity is a highly debated topic, let us assume, for the purposes of this article, that the payment is the only option other than closing your business. Please note, Arete is not advocating to pay ransoms; the choice is entirely a business decision to pursue. This article is intended to provide insight into the various types of decryptors the threat groups provide to unlock your files. We will discuss specific decryptors for some of the more popular variants as well as address subtle nuances between the decryptors.

Full Disk Encryption

Ransomware variants like THT, Mamba, or MCrypt use native or opensource encryption software to encrypt the entire hard drive of the system. Once the TA gains access to the system with administrator privileges, the TA will use a tool like Bestcrypt, DiskCryptor or even Windows Bitlocker to encrypt the full disk. Once encryption is complete, the system reboots and the victims are locked out.

Communication preference: Email usually protonmail, firemail.cc, or cock.li domains

Average ransom payment: $36,000 – $55,000

Preferred currency: Bitcoin (BTC)

Decryptor received: 100% of the time. TA will provide passwords per system for access

Watch out: MCrypt will hold volumes hostage and “re-extort” victims into making multiple payments. During the initial negotiation, the TA will not indicate multiple drives are encrypted. Instead they will negotiate a single amount for initial access to the Operating System; essentially allowing access into Windows. Once access to Windows is regained, victims often surprised to find their “data” partitions are encrypted causing the victim to return to the negotiation table to once again shell out more money to unlock their information.

Notes: After gaining access, the open source encryption tool still needs to be removed otherwise after reboot, the data storage will be locked again.

System Specific Encryption

Ransomware variants like Phobos, Dharma or CryLock are file level encryption. The TA gains access to the system, copies specific encryption executables onto the systems then runs the executables to encrypt the files. The results are files with a new extension appended to the old file name. Sometimes it’s a random sequence of numbers and letters (e.g. *.nocv) or a specific tag (e.g. *[CryLockDecrypt@****.com][1].[ID-*****- COM]). System specific encryption generates a unique key per encrypted system. The ransom note or the file extension may indicate an “ID” that would be different on each system.

CryLock Scanner & Decryptor

Communication preference: Email usually aol.com, protonmail.com, or cock.li domains

Average ransom payment: $27,000 – $500,000

Preferred currency: Bitcoin (BTC)

Decryptor Received: 95% of the time. Certain variants of Phobos and Dharma will attempt to re-extort a second payment if a large discount is negotiated.

Watch out: Phobos, Dharma, and CryLock are a two-step process. The TA will first send a “scanner” tool that needs to be run on every infected system. The scanner will look for the public keys used to encrypt the files, then write that information to a corresponding .txt or .ini file. Those corresponding files need to be sent to the TA in order to generate a decryptor. The TA in return will send the decryptors. The two-step process adds significant overhead due to the running of multiple tools on the infected system as well as the delay with communicating via email. On average after making a payment for the decryptor, clients are who are infected with Phobos are down for approximately 11 days whereas clients who are infected with Dharma experience downtime of about 7.75 days. The high number of days can be attributed to the two-step process and multiple email communications.

Notes: Negotiating with the Phobos and Dharma group can be tricky. These variants are Ransom-as-a-Service (RaaS) model so you’re not dealing with the same core group of people as you would with variants like Ryuk (or now Conti). Negotiating with RaaS groups can also create confusion and complexities with a different operator responding to each email. The groups who deploy these variants also look for exploiting publicly accessible Remote Desktop Protocol (RDP). Disable external access to RDP to lessen the chance of being infected by this variant.

System Specific Encryption with a Universal Option

Ransomware variants like Sodinokibi are file level encryption with a unique ID per system. Once the TA gains access to the network, they release their Sodinokibi ransomware throughout the environment. The systems are infected with a unique randomly generated file extension per system. Their ransom notes are usually within a text file and explain what happened, including if any data was exfiltrated. The group is very organized and can often share information about their victim’s networks including domain information, infected systems, and any stolen data.

Sodinokibi Decryptor

Communication preference: TOR Website via chat room. The ransom note contains a link to the TOR site as well as a unique key to gain access to a private chat room where the negotiations occur.

Average ransom payment: $170,000

Preferred currency: Monero (XMR)

Decryptor received: 100% of the time. Sodin offers a general decryptor which requires the victim to collect the file extensions from all of their infected systems. This can be very tedious once the payment is made, the victim can input any number of file extensions into the input box on the TOR site to generate a decryptor. Sodin will keep that private room open for 30 days after payment allowing victims to return if they find any extensions not previously found. A lesser known secret with Sodin, if you ask nicely for a universal decryptor, the operator may create the decryptor for you; providing a single decryptor that can be used across your network. The universal decryptor certainly saves a lot of time with decrypting files and minimizing the number of times having to launch the TOR browser.

Watch out: Earlier this year, Sodin changed their code base for their encryption payloads causing instability on certain Windows Operating Systems within the master boot files. Using certain security tools after a Sodin outbreak can cause systems to hang during reboot. Sodin encryption is one of the more aggressive encryptions.

Be sure to create a snapshot or backup the files prior to installing any new software or performing live forensics on critical systems.

Notes: Sodin has made headlines throughout 2020 for following Maze with exfiltrating data as well as being the first ransomware group to only accept Monero for payments.

System Specific Encryption with a Universal Option

Sodinokibi Decryptor

Communication preference: TOR Website via chat room. The ransom note contains a link to the TOR site as well as a unique key to gain access to a private chat room where the negotiations occur.

Average ransom payment: $170,000

Preferred currency: Monero (XMR)

Be sure to create a snapshot or backup the files prior to installing any new software or performing live forensics on critical systems.

Notes: Sodin has made headlines throughout 2020 for following Maze with exfiltrating data as well as being the first ransomware group to only accept Monero for payments. eir.co

Universal Encryption

Ransomware variants like Ryuk, WastedLocker, and Dopplepaymer are also file level encryption. These groups will gain access to the network and perform reconnaissance to identify the victim, understand their business, identify critical systems, and delete backups to force their victims into making a payment. The groups can have access to the network for a few hours or upwards of over a month. Ryuk is commonly associated with precursor trojans such as Trickbot and Emotet. Arete has observed Ryuk deployed as quickly as 6 hours after a Trickbot infection. Ryuk infections result with *.ryk appended to the file name. Comparatively, the deployment of WastedLocker is much more calculated with the TA staying on the network for an average of 2 weeks from initial infection to ransomware deployment. Wasted infections result with *.abcwasted appended to the file name where “abc” is a 3 letter abbreviation relating directly to the victims name.

WastedLocker Decryptor

Communication preference: Email usually protonmail.com domains or TOR Website

Average ransom payment: Ryuk $598,000; WastedLocker $2,400,000; Dopplepaymer $304,000

Preferred currency: Bitcoin (BTC)

Decryptor received: 100% of the time. The decryptor received is universal. It is typically a 32-bit executable that will work on any windows OS version. While these groups are known for a high ransom price, their decryptor is probably the simplest to run.

Watch out: WastedLocker is extremely difficult to negotiate. In fact, if negotiation is attempted, they may threaten to increase the ransom by approximately 5% of the ransom per day until it is paid. They are also very slow to respond to email and even post their business hours of UTC 5am- 8am and 5pm-8pm.

Notes: Dopplepaymer has been linked to gaining access to large environments and deploying cryptomining malware before launching their ransomware attack.

Pro Tips to Prevent Ransomware

Attacks

Implement Endpoint, Detection, and Response software such as SentinelOne to monitor the computer systems in use by your organization. SentinelOne uses Artificial Intelligence technology to detect malicious actions and prevent them before they can severely affect the endpoint.
Leverage a Security Operations Center (“SOC”) to monitor computer systems 24 hours a day by 7 days a week. The SOC can instantly respond to triage and mitigate any alerts while keeping your IT personnel focused on maintain business productivity.
Enable Multi-Factor Authentication (“MFA”) on remote access technologies such as VPN and Email.
Use complex passwords with a minimum of 16 alphanumeric characters (non- dictionary words).
Don’t reuse passwords.
Encourage discussion about cybersecurity within the workplace including establishing end user awareness training.
Ensure backups are current, air gapped from the production network, and viable.

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Article

Feb 20, 2026

Threat Actors Leveraging Gemini AI for All Attack Stages

State-backed threat actors are leveraging Google’s Gemini AI as a force multiplier to support all stages of the cyberattack lifecycle, from reconnaissance to post-compromise operations. According to the Google Threat Intelligence Group (GTIG), threat actors linked to the People’s Republic of China (PRC), Iran, North Korea, and other unattributed groups have misused Gemini to accelerate target profiling, synthesize open-source intelligence, identify official email addresses, map organizational structures, generate tailored phishing lures, translate content, conduct vulnerability testing, support coding tasks, and troubleshoot malware development. Cybercriminals are increasingly exploring AI-enabled tools and services to scale malicious activities, including social engineering campaigns such as ClickFix, demonstrating how generative AI is being integrated into both espionage and financially motivated threat operations.

What’s Notable and Unique

Threat actors are leveraging Gemini beyond basic reconnaissance, using it to generate polished, culturally nuanced phishing lures and sustain convincing multi-turn social engineering conversations that minimize traditional red flags.
In addition, threat actors rely on Gemini for vulnerability research, malware debugging, code generation, command-and-control development, and technical troubleshooting, with PRC groups emphasizing automation and vulnerability analysis, Iranian actors focusing on social engineering and malware development, and North Korean actors prioritizing high-fidelity target profiling.
Beyond direct operational support, adversaries have abused public generative AI platforms to host deceptive ClickFix instructions, tricking users into pasting malicious commands that deliver macOS variants of ATOMIC Stealer.
AI is also being integrated directly into malware development workflows, as seen with CoinBait’s AI-assisted phishing kit capabilities and HonestCue’s use of the Gemini API to dynamically generate and execute in-memory C# payloads.
Underground forums show strong demand for AI-powered offensive tools, with offerings like Xanthorox falsely marketed as custom AI but actually built on third-party commercial models integrated through open-source frameworks such as Crush, Hexstrike AI, LibreChat-AI, and Open WebUI, including Gemini.

Analyst Comments

The increasing misuse of generative AI platforms like Gemini highlights a rapidly evolving threat landscape in which state-backed and financially motivated actors leverage AI as a force multiplier for reconnaissance, phishing, malware development, and post-compromise operations. At the same time, large-scale model extraction attempts and API abuse demonstrate emerging risks to AI service integrity, intellectual property, and the broader AI-as-a-Service ecosystem. While these developments underscore the scalability and sophistication of AI-enabled threats, continued enforcement actions, strengthened safeguards, and proactive security testing by providers reflect ongoing efforts to mitigate abuse and adapt defenses in response to increasingly AI-driven adversaries.

Sources

GTIG AI Threat Tracker: Distillation, Experimentation, and (Continued) Integration of AI for Adversarial Use

Article

Feb 12, 2026

2025 VMware ESXi Vulnerability Exploited by Ransomware Groups

Ransomware groups are actively exploiting CVE‑2025‑22225, a VMware ESXi arbitrary write vulnerability that allows attackers to escape the VMX sandbox and gain kernel‑level access to the hypervisor. Although VMware (Broadcom) patched this flaw in March 2025, threat actors had already exploited it in the wild, and CISA recently confirmed that threat actors are exploiting CVE‑2025‑22225 in active campaigns.

What’s Notable and Unique

Chinese‑speaking threat actors abused this vulnerability at least a year before disclosure, via a compromised SonicWall VPN chain.
Threat researchers have observed sophisticated exploit toolkits, possibly developed well before public disclosure, that chain this bug with others to achieve full VM escape. Evidence points to targeted activity, including exploitation via compromised VPN appliances and automated orchestrators.
Attackers with VMX level privileges can trigger a kernel write, break out of the sandbox, and compromise the ESXi host. Intrusions observed in December 2025 showed lateral movement, domain admin abuse, firewall rule manipulation, and staging of data for exfiltration.
CISA has now added CVE-2025-22225 to its Known Exploited Vulnerabilities (KEV) catalog, underscoring ongoing use by ransomware attackers.

Analyst Comments

Compromise of ESXi hypervisors significantly amplifies operational impact, allowing access to and potential encryption of dozens of VMs simultaneously. Organizations running ESXi 7.x and 8.x remain at high risk if patches and mitigations have not been applied. Therefore, clients are recommended to apply VMware patches from VMSA‑2025‑0004 across all ESXi, Workstation, and Fusion deployments. Enterprises are advised to assess their setups in order to reduce risk, as protecting publicly accessible management interfaces is a fundamental security best practice.

Sources

CVE-2025-22225 in VMware ESXi now used in active ransomware attacks
The Great VM Escape: ESXi Exploitation in the Wild
VMSA-205-004: VMware ESXi, Workstation, and Fusion updates address multiple vulnerabilities (CVE-205-22224, CVE-2025-22225, CVE-2025-22226)

Article

Feb 5, 2026

Ransomware Trends & Data Insights: January 2026

Although Akira was once again the most active ransomware group in January, the threat landscape was more evenly distributed than it was throughout most of 2025. In December 2025, the three most active threat groups accounted for 57% of all ransomware and extortion activity; in January, the top three accounted for just 34%. Akira’s dominance also decreased to levels more consistent with early 2025, as the group was responsible for almost a third of all attacks in December but just 17% in January.

The number of unique ransomware and extortion groups observed in January increased slightly, to 17, up from 14 in December. It is too early to assess whether this trend will be the new normal for 2026. It is also worth noting that overall activity in January was lower than in previous months, consistent with what Arete typically observes at the beginning of a new year.

Figure 1. Activity from all threat groups in January 2026

Throughout the month of January, analysts at Arete identified several distinct trends behind the threat actors perpetrating cybercrime activities:

In January, Arete observed the reemergence of the LockBit Ransomware-as-a-Service (RaaS) group, which deployed an updated “LockBit 5.0” variant of its ransomware. LockBit first announced the 5.0 version on the RAMP dark web forum in early September 2025, coinciding with the group’s six-year anniversary. The latest LockBit 5.0 variant has both Windows and Linux versions, with notable improvements, including anti-analysis features and unique 16-character extensions added to each encrypted file. However, it remains to be seen whether LockBit will return to consistent activity levels in 2026.

The ClickFix social engineering technique, which leverages fake error dialog boxes to deceive users into manually executing malicious PowerShell commands, continued to evolve in unique ways in January. One campaign reported in January involved fake Blue Screen of Death (BSOD) messages manipulating users into pasting attacker-controlled code. During the month, researchers also documented a separate campaign, dubbed “CrashFix,” that uses a malicious Chrome browser extension-based attack vector. It crashes the web browser, displays a message stating the browser had "stopped abnormally," and then prompts the victim to click a button that executes malicious commands.

Also in January, Fortinet confirmed that a new critical authentication vulnerability affecting its FortiGate devices is being actively exploited. The vulnerability, tracked as CVE-2026-24858, allows attackers with a FortiCloud account to log in to devices registered to other account owners due to an authentication bypass flaw in devices using FortiCloud single sign-on (SSO). This recent activity follows the exploitation of two other Fortinet SSO authentication flaws, CVE-2025-59718 and CVE-2025-59719, which were disclosed in December 2025.

Source

Arete Internal

Article

Feb 2, 2026

New FortiCloud SSO Vulnerability Exploited

Fortinet recently confirmed that its FortiGate devices are affected by a new critical authentication vulnerability that is being actively exploited. The vulnerability, tracked as CVE-2026-24858, allows attackers with a FortiCloud account to log in to devices registered to other account owners due to an authentication bypass flaw in devices using FortiCloud single sign-on (SSO). CISA added the vulnerability to its Known Exploited Vulnerabilities catalogue and gave federal agencies just three days to patch, which requires users to upgrade all devices running FortiOS, FortiManager, FortiAnalyzer, FortiProxy, and FortiWeb to fixed versions. This recent activity follows the exploitation of two other SSO authentication flaws, CVE-2025-59718 and CVE-2025-59719, which were disclosed last month.

What’s Notable and Unique

There are strong indications that much of the recent exploitation activity was automated, with attackers moving from initial access to account creation within seconds.
As observed in December 2025, the attackers’ primary target appears to be firewall configuration files, which contain a trove of information that can be leveraged in future operations.
The threat actors in this campaign favor innocuous, IT-themed email and account names, with malicious login activity originating from cloud-init@mail[.]io and cloud-noc@mail[.]io, while account names such as ‘secadmin’, ‘itadmin’, ‘audit’, and others are created for persistence and subsequent activity.

Analyst Comments

This is an active campaign, and the investigation into these attacks is ongoing. Organizations relying on FortiGate devices should remain extremely vigilant, even after following patching guidance. With threat actors circumventing authentication, it’s crucial to monitor for and alert on anomalous behavior within your environment, such as the unauthorized creation of admin accounts, the creation or modification of access policies, logins outside normal working hours, and anything that deviates from your security baseline.

Sources

Administrative FortiCloud SSO authentication bypass
Multiple Fortinet Products’ FortiCloud SSO Login Authentication Bypass
Arctic Wolf Observes Malicious Configuration Changes On Fortinet FortiGate Devices via SSO Accounts
Arctic Wolf Observes Malicious SSO Logins on FortiGate Devices Following Disclosure of CVE-2025-59718 and CVE-2025-59719

Article

Ransomware Decryptors for a (varying) fee

Full Disk Encryption

System Specific Encryption

System Specific Encryption with a Uni­versal Option

System Specific Encryption with a Uni­versal Option

Universal Encryption

Pro Tips to Prevent Ransomware

Attacks

Article

Feb 20, 2026

Threat Actors Leveraging Gemini AI for All Attack Stages

What’s Notable and Unique

Analyst Comments

Sources

Article

Feb 12, 2026

2025 VMware ESXi Vulnerability Exploited by Ransomware Groups

What’s Notable and Unique

Analyst Comments

Sources

Article

Feb 5, 2026

Ransomware Trends & Data Insights: January 2026

Source

Article

Feb 2, 2026

New FortiCloud SSO Vulnerability Exploited

What’s Notable and Unique

Analyst Comments

Sources

System Specific Encryption with a Universal Option

System Specific Encryption with a Universal Option