Chaos Builder (Exploit Kit) – Malware

Overview

The Chaos Builder malware, a versatile and evolving tool, has emerged as one of the most concerning threats in the world of ransomware-as-a-service (RaaS) operations. Originating from the underground cybercrime world, Chaos Builder enables cybercriminals to develop and deploy highly effective ransomware payloads with relative ease. Unlike more traditional ransomware development processes that demand sophisticated technical expertise, Chaos Builder’s user-friendly interface empowers even relatively novice threat actors to launch destructive attacks against unsuspecting victims. The builder has garnered attention due to its ability to create highly configurable and adaptable ransomware strains, which have been observed in a growing number of real-world attacks.

The Chaos Builder malware operates by providing its users with a toolkit to craft malicious payloads designed to infiltrate and cripple target systems. These payloads are often distributed through common tactics such as phishing emails, drive-by downloads, and compromised websites, making the malware highly effective in reaching a wide range of victims. Once deployed, Chaos Builder-based ransomware encrypts files, locks systems, and displays ransom demands. This modular and customizable nature of the malware makes it a highly attractive option for both cybercriminals seeking to maximize financial gain and for hacktivists using it for ideological purposes.

Targets

Information

Individuals

How they operate

Chaos Builder typically gains initial access through phishing campaigns, often carried out via email. These emails usually contain malicious attachments or links that, when clicked, trigger the malware’s execution. The attachments might be disguised as legitimate documents or compressed files, which, once opened, unleash a dropper onto the system. The dropper is a small, self-contained malware that, when executed, silently installs the full Chaos Builder payload on the victim’s device. Additionally, some variants of the malware can exploit web-based vulnerabilities, employing a drive-by compromise method to infect users without requiring user interaction. This can happen when a user visits a compromised website containing an exploit kit that takes advantage of weaknesses in outdated software or browsers.

Once the initial access is achieved, Chaos Builder utilizes command and scripting interpreters like PowerShell or batch files to execute further commands. These scripts typically help the malware evade detection by executing additional payloads and commands in a way that mimics legitimate system activity. In many instances, the malware runs silently in the background, avoiding user interaction unless required for file encryption or ransom notes.

To maintain persistence and evade detection, Chaos Builder establishes backdoors and scheduled tasks on the compromised system. These mechanisms ensure that the malware remains operational even after system reboots or user logoffs. By modifying system processes or creating new registry keys, the malware ensures that it is automatically executed every time the system starts up, providing it with continuous access to the infected environment. Additionally, some variants attempt privilege escalation by exploiting system vulnerabilities or bypassing user account control mechanisms to gain administrator-level access, which allows for more extensive manipulation of the system.

Once the malware has established a foothold on the victim system, it may attempt to gain further access by stealing or harvesting credentials. Chaos Builder can deploy credential dumping techniques to gather usernames, passwords, or other authentication tokens stored within the system. These stolen credentials can be used to escalate the malware’s access level, allowing it to move laterally across the network and target additional machines. This lateral movement is particularly effective in environments with weak segmentation or misconfigured security policies, enabling the attacker to expand their reach quickly.

In cases where the malware spreads across a network, it may exploit services like Windows SMB or RDP (Remote Desktop Protocol) to propagate. By gaining access to higher-value systems or databases, the attacker increases the overall impact of the infection, potentially holding more sensitive data for ransom.

The hallmark of Chaos Builder malware is its ability to encrypt files on the compromised system. Once the malware has escalated privileges and ensured persistence, it begins encrypting files, often targeting specific file types that contain sensitive data—such as documents, spreadsheets, databases, and images. The encryption process is typically strong, using asymmetric encryption algorithms that generate a unique decryption key for each infected system. Victims are left with an unopenable file structure and a ransom note demanding payment in cryptocurrency for the decryption key.

In addition to encryption, Chaos Builder can also exfiltrate data, which could either be used for double extortion or be sold on the dark web. Exfiltration is often done through command and control (C2) channels, which are encrypted to avoid detection. The malware can send stolen files or credentials to external servers controlled by the attackers, who then decide how to leverage the data for maximum gain.

To evade detection by security software, Chaos Builder employs various defense evasion techniques. The malware often uses obfuscation methods to hide its true nature from antivirus programs and endpoint detection systems. This could involve encrypting its code or using polymorphic tactics, where the malware alters its code slightly with each infection to avoid signature-based detection. Additionally, Chaos Builder may disable or circumvent security solutions like firewalls and antivirus software to ensure its payload remains undetected.

Moreover, the malware often seeks to disrupt any potential recovery efforts. By deleting or disabling volume shadow copies, it prevents victims from restoring their files through traditional backup mechanisms. This makes the demand for a ransom payment more compelling, as it reduces the victim’s ability to recover data independently.

MITRE Tactics and Techniques

1. Initial Access

Phishing (T1566): Chaos Builder is often distributed via phishing emails that contain malicious attachments or links, which, when clicked, lead to the execution of the malware.

Drive-by Compromise (T1189): Chaos Builder can also be delivered through compromised websites or malicious ads that automatically exploit vulnerabilities in the victim’s browser or system when visited.

2. Execution

Command and Scripting Interpreter (T1059): The malware frequently leverages scripting languages, such as PowerShell or batch files, to execute commands that deliver the ransomware payload. This could involve executing a dropper or other malicious scripts that initiate the ransomware attack.

User Execution (T1204): In some cases, the ransomware relies on user interaction (e.g., opening a malicious attachment or clicking on a link) to execute the payload, which is common with drive-by downloads or phishing attacks.

3. Persistence

Create or Modify System Process (T1543): Chaos Builder often establishes persistence by creating new startup entries or modifying system processes to ensure that the ransomware payload is executed upon system restart.

Scheduled Task/Job (T1053): Some variants of Chaos Builder may use scheduled tasks to ensure the malware remains persistent on the system, enabling it to run periodically or upon system startup.

4. Privilege Escalation

Exploitation for Privilege Escalation (T1068): Chaos Builder may exploit vulnerabilities in the system to elevate its privileges and gain administrator-level access, allowing it to execute its ransomware more effectively.

Bypass User Account Control (T1548): It may attempt to bypass UAC to gain elevated privileges silently and avoid detection during execution.

5. Defense Evasion

Obfuscated Files or Information (T1027): Chaos Builder often employs obfuscation techniques to avoid detection by security tools. This includes encrypting or disguising the ransomware code to prevent it from being flagged by antivirus or security solutions.

Disabling Security Tools (T1089): It can disable antivirus or endpoint detection software to avoid detection and prolong the infection.

Virtual Machine Detection (T1497): To avoid analysis, the malware might check for virtual environments (e.g., sandboxing or analysis environments) and evade execution in those contexts.

6. Credential Access

Credential Dumping (T1003): In some instances, Chaos Builder may attempt to dump user credentials from the system to facilitate lateral movement or escalate privileges during the attack.

7. Exfiltration

Exfiltration Over Command and Control Channel (T1041): Though not always a primary objective, in some cases, Chaos Builder may facilitate the exfiltration of sensitive data over the same channel used for the malware’s command and control communications.

8. Impact

Data Encrypted for Impact (T1486): The primary function of Chaos Builder is to encrypt files on the target system, rendering them inaccessible until the ransom is paid.

System Shutdown/Reboot (T1509): Some variants may force a system shutdown or reboot to disrupt operations or further complicate recovery efforts.

Inhibit System Recovery (T1490): It may disable or delete volume shadow copies to prevent victims from recovering their data without paying the ransom.

References:

• DeathGrip RaaS | Small-Time Threat Actors Aim High With LockBit & Yashma Builders