Tales from the Dark Web: How Tracking eCrime’s Underground Economy Improves Defenses

Originally published by CrowdStrike here.

Written by Bart Lenaerts-Bergmans, CrowdStrike.

Ransomware is not new; adversarial groups have relied on compromises for many years. However, over the past 2-3 years, their strategy has started to shift toward a more community based business model enabled by ransomware-as-a-service (RaaS) platforms that allow smaller, less advanced criminals to join a larger operation.

At the top of this model is an operator who sets up a RaaS platform that takes care of multiple technical tasks such as on-demand ransomware packaging, command and control of deployed ransomware, cryptography, data extraction, archiving, online extortion and others.

Less sophisticated cybercriminals with minimal hacking knowledge can join this operation after being vetted; when they do, they’ll receive 70 to 80% of the paid ransom. These emerging criminals are also assisted by access brokers, through which they can acquire access to the infrastructure of a potential victim. The interaction between all these criminal entities — RaaS operators, vetted affiliates, access brokers and other participants — happen via criminal forums, underground markets and anonymous posts.

Access Brokers: How Adversaries Get In

The eCrime kill chain is often enabled by access brokers, the intruders who gain access to an organization’s infrastructure and then sell illicitly obtained credentials and other access methods to buyers in underground communities.

Adversaries buy compromised credentials to make the process of getting into a target organization easier and more efficient. Access brokers sell a broad range of access types, including financial account logins, business email account credentials, remote access to network assets and custom exploits for IT infrastructure.

To advertise compromised credentials and other access methods on the underground, access brokers use particular keywords and target specific marketplaces. However, their posts often leave behind “breadcrumbs” that offer defenders an opportunity to detect compromised accounts or risks of security incidents. For example, an access broker may include attributes such as company details (size, revenue, industry), IT infrastructure details, the malware used to steal credentials, or the access broker’s alias.

The amount of chatter on underground forums is massive.

Distribution Services: A Force Driving Ransomware

Analysis of ransomware campaigns by groups such as Pinchy Spider, also known as REvil, Wizard Spider (Conti) and Carbon Spider (DarkSide) has made it clear the operators behind these campaigns no longer work alone, in particular when compromising assets and injecting the ransomware. Ransomware operators advertise on underground forums to recruit affiliates who can help them distribute ransomware and share the profits.

These affiliates leverage RaaS infrastructure from the operators. After targeting and compromising a victim’s assets, they drop ransomware from the RaaS platform, set the ransom demand and get 70 to 80% of the ransom payment in return. Victims are often chosen based on the likelihood they’ll be able to afford a ransom; affiliates often calculate ransom payouts based on company revenue and business impact to maximize their profits.

Operators provide technical services in return for affiliates’ help in distributing ransomware. They may provide a packager to generate customized ransomware so affiliates can distribute over their own channels; cryptographic key management; or internet infrastructure for data exfiltration and storage. They may share payment instructions to receive virtual currencies from victims; secret communication channels to hide affiliates when they talk to victims; and even a help desk to aid victims in paying the ransom. These services give a boost to less tech-savvy adversaries, who benefit from access to technically advanced malware at low cost.

CrowdStrike Intelligence analysts found multiple initial access and lateral movement techniques that affiliates use before deploying ransomware. By changing how they distribute ransomware, adversaries can find new ways to bypass security measures. Below are a few examples of how attackers gain initial access:

• Buying stolen credentials from access brokers. Affiliates often use legitimate credentials to gain a foothold. Remote Desktop Protocol (RDP) is a popular entryway.
• Spam or social engineering. Among the most common initial access vectors.
• Vulnerability scanning and exploit kits. These kits can be found on multiple forums and target specific software or systems to gain access and install additional code . Exploit kits can be combined with phishing campaigns to boost their effectiveness.
• Loader and botnet usage. Loaders, often a step between phishing campaigns and ransomware deployment, use malicious documents like macro-enabled spreadsheets to download and execute malicious code.
• Post-exploitation tools and “living off the land.” Adversaries that access a system will explore the network to find critical data or applications that can help further an attack. Some use system tools like PSExec or PowerShell scripts to remain hidden.

A better understanding of adversary techniques can help improve your defenses. Organizations must know which attackers are targeting their region or industry, whether they are recruiting affiliates, and how their ransomware is distributed. By understanding the adversary and their tools, defenders can employ an intelligence-first defense strategy based on the threats they face.

Monetization: How Cybercrime Pays

Once ransomware is deployed into a victim environment, the prize needs to be split and monetized into other payment forms. Adversaries constantly evolve their monetization techniques to maximize the chance of payment. Their methods are working: reports from the U.S. Treasury Department’s Financial Crimes Enforcement Network (FinCen) and the Office of Foreign Assets Control (OFAC) underscore how lucrative ransomware has become. FinCen found the value of suspicious activity detailed in ransomware-related suspicious activity reports (SARs) was $590 million USD in the first six months of 2021 — far higher than the $416 million USD reported in all of 2020. Further, CrowdStrike’s Intelligence team also tracks ransomware demands: in 2021, we calculated an average demand of $6.1 million USD, an increase of 36% from 2020.

If a victim refuses to pay ransom, their data may be auctioned by the threat actor so they can still make money on it by selling it to other parties or adversaries.

Corporate data is valuable to all adversaries. Once they have it, the data can be easily monetized and present increased risk to your organization if other attackers have access to it. Defenders must develop a stronger understanding of cybercriminals’ behavior — and the broader eCrime ecosystem — in order to make smarter security decisions that best protect data as their most valuable asset.