Threeam Ransomware

Adversaries may create an account to maintain access to victim systems. With a sufficient level of access, creating such accounts may be used to establish secondary credentialed access that do not require persistent remote access tools to be deployed on the system. Accounts may be created on the local system or within a domain or cloud tenant. In cloud environments, adversaries may create accounts that only have access to specific services, which can reduce the chance of detection.

Mitigations: Operating System Configuration, Network Segmentation, Privileged Account Management, Multi-factor Authentication

Adversaries may abuse the Windows service control manager to execute malicious commands or payloads. The Windows service control manager (<codeservices.exe</code) is an interface to manage and manipulate services. The service control manager is accessible to users via GUI components as well as system utilities such as <codesc.exe</code and Net. PsExec can also be used to execute commands or payloads via a temporary Windows service created through the service control manager API. Tools such as PsExec and <codesc.exe</code can accept remote servers as arguments and may be used to conduct remote execution. Adversaries may leverage these mechanisms to execute malicious content.

Mitigations: Behavior Prevention on Endpoint, Restrict File and Directory Permissions, Privileged Account Management

Adversaries may bypass UAC mechanisms to elevate process privileges on system. Windows User Account Control (UAC) allows a program to elevate its privileges (tracked as integrity levels ranging from low to high) to perform a task under administrator-level permissions, possibly by prompting the user for confirmation. The impact to the user ranges from denying the operation under high enforcement to allowing the user to perform the action if they are in the local administrators group and click through the prompt or allowing them to enter an administrator password to complete the action.

Mitigations: User Account Control, Privileged Account Management, Audit, Update Software

Adversaries may attempt to get a listing of other systems by IP address, hostname, or other logical identifier on a network that may be used for Lateral Movement from the current system. Functionality could exist within remote access tools to enable this, but utilities available on the operating system could also be used such as Ping, <codenet view</code using Net, or, on ESXi servers, esxcli network diag ping. Adversaries may also analyze data from local host files (ex: <codeC:\Windows\System32\Drivers\etc\hosts</code or <code/etc/hosts</code) or other passive means (such as local Arp cache entries) in order to discover the presence of remote systems in an environment.

Adversaries may look for folders and drives shared on remote systems as a means of identifying sources of information to gather as a precursor for Collection and to identify potential systems of interest for Lateral Movement. Networks often contain shared network drives and folders that enable users to access file directories on various systems across a network. File sharing over a Windows network occurs over the SMB protocol. Net can be used to query a remote system for available shared drives using the <codenet view \\\\remotesystem</code command. It can also be used to query shared drives on the local system using <codenet share</code.

Mitigations: Operating System Configuration

Adversaries may gather information on Group Policy settings to identify paths for privilege escalation, security measures applied within a domain, and to discover patterns in domain objects that can be manipulated or used to blend in the environment. Group Policy allows for centralized management of user and computer settings in Active Directory (AD). Group policy objects (GPOs) are containers for group policy settings made up of files stored within a predictable network path \<DOMAIN\SYSVOL\<DOMAIN\Policies\.

Adversaries may steal data by exfiltrating it over a different protocol than that of the existing command and control channel. The data may also be sent to an alternate network location from the main command and control server. Alternate protocols include FTP, SMTP, HTTP/S, DNS, SMB, or any other network protocol not being used as the main command and control channel. Adversaries may also opt to encrypt and/or obfuscate these alternate channels. Exfiltration Over Alternative Protocol can be done using various common operating system utilities such as Net/SMB or FTP. On macOS and Linux <codecurl</code may be used to invoke protocols such as HTTP/S or FTP/S to exfiltrate data from a system.

Mitigations: Network Intrusion Prevention, Filter Network Traffic, Data Loss Prevention, Network Segmentation, User Account Management, Restrict File and Directory Permissions

Adversaries may encrypt data on target systems or on large numbers of systems in a network to interrupt availability to system and network resources. They can attempt to render stored data inaccessible by encrypting files or data on local and remote drives and withholding access to a decryption key. This may be done in order to extract monetary compensation from a victim in exchange for decryption or a decryption key (ransomware) or to render data permanently inaccessible in cases where the key is not saved or transmitted.

Mitigations: Data Backup, Behavior Prevention on Endpoint