Enterprise sub-techniques

Adversaries may use Valid Accounts to interact with a remote network share using Server Message Block (SMB). The adversary may then perform actions as the logged-on user.

SMB is a file, printer, and serial port sharing protocol for Windows machines on the same network or domain. Adversaries may use SMB to interact with file shares, allowing them to move laterally throughout a network. Linux and macOS implementations of SMB typically use Samba.

Windows systems have hidden network shares that are accessible only to administrators and provide the ability for remote file copy and other administrative functions. Example network shares include `C$`, `ADMIN$`, and `IPC$`. Adversaries may use this technique in conjunction with administrator-level Valid Accounts to remotely access a networked system over SMB,[1] to interact with systems using remote procedure calls (RPCs),[2] transfer files, and run transferred binaries through remote Execution. Example execution techniques that rely on authenticated sessions over SMB/RPC are Scheduled Task/Job, Service Execution, and Windows Management Instrumentation. Adversaries can also use NTLM hashes to access administrator shares on systems with Pass the Hash and certain configuration and patch levels.[3]

Adversaries may leverage messaging services for SMS pumping, which may impact system and/or hosted service availability.[1] SMS pumping is a type of telecommunications fraud whereby a threat actor first obtains a set of phone numbers from a telecommunications provider, then leverages a victim’s messaging infrastructure to send large amounts of SMS messages to numbers in that set. By generating SMS traffic to their phone number set, a threat actor may earn payments from the telecommunications provider.[2]

Threat actors often use publicly available web forms, such as one-time password (OTP) or account verification fields, in order to generate SMS traffic. These fields may leverage services such as Twilio, AWS SNS, and Amazon Cognito in the background.[1][3] In response to the large quantity of requests, SMS costs may increase and communication channels may become overwhelmed.[1]

Adversaries may target the Management Information Base (MIB) to collect and/or mine valuable information in a network managed using Simple Network Management Protocol (SNMP).

The MIB is a configuration repository that stores variable information accessible via SNMP in the form of object identifiers (OID). Each OID identifies a variable that can be read or set and permits active management tasks, such as configuration changes, through remote modification of these variables. SNMP can give administrators great insight in their systems, such as, system information, description of hardware, physical location, and software packages[1]. The MIB may also contain device operational information, including running configuration, routing table, and interface details.

Adversaries may use SNMP queries to collect MIB content directly from SNMP-managed devices in order to collect network information that allows the adversary to build network maps and facilitate future targeted exploitation.[2][3]

Adversaries may abuse SQL stored procedures to establish persistent access to systems. SQL Stored Procedures are code that can be saved and reused so that database users do not waste time rewriting frequently used SQL queries. Stored procedures can be invoked via SQL statements to the database using the procedure name or via defined events (e.g. when a SQL server application is started/restarted).

Adversaries may craft malicious stored procedures that can provide a persistence mechanism in SQL database servers.[1][2] To execute operating system commands through SQL syntax the adversary may have to enable additional functionality, such as xp_cmdshell for MSSQL Server.[1][2][3]

Microsoft SQL Server can enable common language runtime (CLR) integration. With CLR integration enabled, application developers can write stored procedures using any .NET framework language (e.g. VB .NET, C#, etc.).[4] Adversaries may craft or modify CLR assemblies that are linked to stored procedures since these CLR assemblies can be made to execute arbitrary commands.[5]

Adversaries may use Valid Accounts to log into remote machines using Secure Shell (SSH). The adversary may then perform actions as the logged-on user.

SSH is a protocol that allows authorized users to open remote shells on other computers. Many Linux and macOS versions come with SSH installed by default, although typically disabled until the user enables it. On ESXi, SSH can be enabled either directly on the host (e.g., via `vim-cmd hostsvc/enable_ssh`) or via vCenter.[1][2][3] The SSH server can be configured to use standard password authentication or public-private keypairs in lieu of or in addition to a password. In this authentication scenario, the user’s public key must be in a special file on the computer running the server that lists which keypairs are allowed to login as that user (i.e., SSH Authorized Keys).

Adversaries may modify the SSH authorized_keys file to maintain persistence on a victim host. Linux distributions, macOS, and ESXi hypervisors commonly use key-based authentication to secure the authentication process of SSH sessions for remote management. The authorized_keys file in SSH specifies the SSH keys that can be used for logging into the user account for which the file is configured. This file is usually found in the user's home directory under <user-home>/.ssh/authorized_keys (or, on ESXi, `/etc/ssh/keys-/authorized_keys`).[1] Users may edit the system’s SSH config file to modify the directives `PubkeyAuthentication` and `RSAAuthentication` to the value `yes` to ensure public key and RSA authentication are enabled, as well as modify the directive `PermitRootLogin` to the value `yes` to enable root authentication via SSH.[2] The SSH config file is usually located under /etc/ssh/sshd_config.

Adversaries may modify SSH authorized_keys files directly with scripts or shell commands to add their own adversary-supplied public keys. In cloud environments, adversaries may be able to modify the SSH authorized_keys file of a particular virtual machine via the command line interface or rest API. For example, by using the Google Cloud CLI’s “add-metadata” command an adversary may add SSH keys to a user account.[3][4] Similarly, in Azure, an adversary may update the authorized_keys file of a virtual machine via a PATCH request to the API.[5] This ensures that an adversary possessing the corresponding private key may log in as an existing user via SSH.[6][7] It may also lead to privilege escalation where the virtual machine or instance has distinct permissions from the requesting user.

Where authorized_keys files are modified via cloud APIs or command line interfaces, an adversary may achieve privilege escalation on the target virtual machine if they add a key to a higher-privileged user.

SSH keys can also be added to accounts on network devices, such as with the `ip ssh pubkey-chain` Network Device CLI command.[8]

Adversaries may hijack a legitimate user's SSH session to move laterally within an environment. Secure Shell (SSH) is a standard means of remote access on Linux and macOS systems. It allows a user to connect to another system via an encrypted tunnel, commonly authenticating through a password, certificate or the use of an asymmetric encryption key pair.

In order to move laterally from a compromised host, adversaries may take advantage of trust relationships established with other systems via public key authentication in active SSH sessions by hijacking an existing connection to another system. This may occur through compromising the SSH agent itself or by having access to the agent's socket. If an adversary is able to obtain root access, then hijacking SSH sessions is likely trivial.[1][2][3][4]

SSH Hijacking differs from use of SSH because it hijacks an existing SSH session rather than creating a new session using Valid Accounts.

Adversaries may smuggle data and files past content filters by hiding malicious payloads inside of seemingly benign SVG files.[1] SVGs, or Scalable Vector Graphics, are vector-based image files constructed using XML. As such, they can legitimately include `` tags that enable adversaries to include malicious JavaScript payloads. However, SVGs may appear less suspicious to users than other types of executable files, as they are often treated as image files.

SVG smuggling can take a number of forms. For example, threat actors may include content that:

* Assembles malicious payloads[2] * Downloads malicious payloads[3] * Redirects users to malicious websites[4] * Displays interactive content to users, such as fake login forms and download buttons.[4]

SVG Smuggling may be used in conjunction with HTML Smuggling where an SVG with a malicious payload is included inside an HTML file.[2] SVGs may also be included in other types of documents, such as PDFs.

Adversaries may abuse Windows safe mode to disable endpoint defenses. Safe mode starts up the Windows operating system with a limited set of drivers and services. Third-party security software such as endpoint detection and response (EDR) tools may not start after booting Windows in safe mode. There are two versions of safe mode: Safe Mode and Safe Mode with Networking. It is possible to start additional services after a safe mode boot.[1][2]

Adversaries may abuse safe mode to disable endpoint defenses that may not start with a limited boot. Hosts can be forced into safe mode after the next reboot via modifications to Boot Configuration Data (BCD) stores, which are files that manage boot application settings.[3]

Adversaries may also add their malicious applications to the list of minimal services that start in safe mode by modifying relevant Registry values (i.e. Modify Registry). Malicious Component Object Model (COM) objects may also be registered and loaded in safe mode.[2][4][5][6]

Adversaries may search within public scan databases for information about victims that can be used during targeting. Various online services continuously publish the results of Internet scans/surveys, often harvesting information such as active IP addresses, hostnames, open ports, certificates, and even server banners.[1]

Adversaries may search scan databases to gather actionable information. Threat actors can use online resources and lookup tools to harvest information from these services. Adversaries may seek information about their already identified targets, or use these datasets to discover opportunities for successful breaches. Information from these sources may reveal opportunities for other forms of reconnaissance (ex: Active Scanning or Search Open Websites/Domains), establishing operational resources (ex: Develop Capabilities or Obtain Capabilities), and/or initial access (ex: External Remote Services or Exploit Public-Facing Application).

Adversaries may scan victim IP blocks to gather information that can be used during targeting. Public IP addresses may be allocated to organizations by block, or a range of sequential addresses.

Adversaries may scan IP blocks in order to Gather Victim Network Information, such as which IP addresses are actively in use as well as more detailed information about hosts assigned these addresses. Scans may range from simple pings (ICMP requests and responses) to more nuanced scans that may reveal host software/versions via server banners or other network artifacts.[1] Information from these scans may reveal opportunities for other forms of reconnaissance (ex: Search Open Websites/Domains or Search Open Technical Databases), establishing operational resources (ex: Develop Capabilities or Obtain Capabilities), and/or initial access (ex: External Remote Services).

Adversaries may abuse the Windows Task Scheduler to perform task scheduling for initial or recurring execution of malicious code. There are multiple ways to access the Task Scheduler in Windows. The schtasks utility can be run directly on the command line, or the Task Scheduler can be opened through the GUI within the Administrator Tools section of the Control Panel.[1] In some cases, adversaries have used a .NET wrapper for the Windows Task Scheduler, and alternatively, adversaries have used the Windows netapi32 library and Windows Management Instrumentation (WMI) to create a scheduled task. Adversaries may also utilize the Powershell Cmdlet `Invoke-CimMethod`, which leverages WMI class `PS_ScheduledTask` to create a scheduled task via an XML path.[2]

An adversary may use Windows Task Scheduler to execute programs at system startup or on a scheduled basis for persistence. The Windows Task Scheduler can also be abused to conduct remote Execution as part of Lateral Movement and/or to run a process under the context of a specified account (such as SYSTEM). Similar to System Binary Proxy Execution, adversaries have also abused the Windows Task Scheduler to potentially mask one-time execution under signed/trusted system processes.[3]

Adversaries may also create "hidden" scheduled tasks (i.e. Hide Artifacts) that may not be visible to defender tools and manual queries used to enumerate tasks. Specifically, an adversary may hide a task from `schtasks /query` and the Task Scheduler by deleting the associated Security Descriptor (SD) registry value (where deletion of this value must be completed using SYSTEM permissions).[4][5] Adversaries may also employ alternate methods to hide tasks, such as altering the metadata (e.g., `Index` value) within associated registry keys.[6]

Adversaries may establish persistence by executing malicious content triggered by user inactivity. Screensavers are programs that execute after a configurable time of user inactivity and consist of Portable Executable (PE) files with a .scr file extension.[1] The Windows screensaver application scrnsave.scr is located in C:\Windows\System32\, and C:\Windows\sysWOW64\ on 64-bit Windows systems, along with screensavers included with base Windows installations.

The following screensaver settings are stored in the Registry (HKCU\Control Panel\Desktop\) and could be manipulated to achieve persistence:

* SCRNSAVE.exe - set to malicious PE path * ScreenSaveActive - set to '1' to enable the screensaver * ScreenSaverIsSecure - set to '0' to not require a password to unlock * ScreenSaveTimeout - sets user inactivity timeout before screensaver is executed

Adversaries can use screensaver settings to maintain persistence by setting the screensaver to run malware after a certain timeframe of user inactivity.[2]

Adversaries may use search engines to collect information about victims that can be used during targeting. Search engine services typical crawl online sites to index context and may provide users with specialized syntax to search for specific keywords or specific types of content (i.e. filetypes).[1][2]

Adversaries may craft various search engine queries depending on what information they seek to gather. Threat actors may use search engines to harvest general information about victims, as well as use specialized queries to look for spillages/leaks of sensitive information such as network details or credentials. Information from these sources may reveal opportunities for other forms of reconnaissance (ex: Phishing for Information or Search Open Technical Databases), establishing operational resources (ex: Establish Accounts or Compromise Accounts), and/or initial access (ex: Valid Accounts or Phishing).

Adversaries may attempt to extract credential material from the Security Account Manager (SAM) database either through in-memory techniques or through the Windows Registry where the SAM database is stored. The SAM is a database file that contains local accounts for the host, typically those found with the net user command. Enumerating the SAM database requires SYSTEM level access.

A number of tools can be used to retrieve the SAM file through in-memory techniques:

* pwdumpx.exe * gsecdump * Mimikatz * secretsdump.py

Alternatively, the SAM can be extracted from the Registry with Reg:

* reg save HKLM\sam sam * reg save HKLM\system system

Creddump7 can then be used to process the SAM database locally to retrieve hashes.[1]

Notes:

* RID 500 account is the local, built-in administrator. * RID 501 is the guest account. * User accounts start with a RID of 1,000+.

Adversaries may attempt to get a listing of security software, configurations, defensive tools, and sensors that are installed on a system or in a cloud environment. This may include things such as cloud monitoring agents and anti-virus. Adversaries may use the information from Security Software Discovery during automated discovery to shape follow-on behaviors, including whether or not the adversary fully infects the target and/or attempts specific actions.

Example commands that can be used to obtain security software information are netsh, reg query with Reg, dir with cmd, and Tasklist, but other indicators of discovery behavior may be more specific to the type of software or security system the adversary is looking for. It is becoming more common to see macOS malware perform checks for LittleSnitch and KnockKnock software.

Adversaries may also utilize the Cloud API to discover cloud-native security software installed on compute infrastructure, such as the AWS CloudWatch agent, Azure VM Agent, and Google Cloud Monitor agent. These agents may collect metrics and logs from the VM, which may be centrally aggregated in a cloud-based monitoring platform.

Adversaries may abuse security support providers (SSPs) to execute DLLs when the system boots. Windows SSP DLLs are loaded into the Local Security Authority (LSA) process at system start. Once loaded into the LSA, SSP DLLs have access to encrypted and plaintext passwords that are stored in Windows, such as any logged-on user's Domain password or smart card PINs.

The SSP configuration is stored in two Registry keys: HKLM\SYSTEM\CurrentControlSet\Control\Lsa\Security Packages and HKLM\SYSTEM\CurrentControlSet\Control\Lsa\OSConfig\Security Packages. An adversary may modify these Registry keys to add new SSPs, which will be loaded the next time the system boots, or when the AddSecurityPackage Windows API function is called.[1]

An adversary with root access may gather credentials by reading `securityd`’s memory. `securityd` is a service/daemon responsible for implementing security protocols such as encryption and authorization.[1] A privileged adversary may be able to scan through `securityd`'s memory to find the correct sequence of keys to decrypt the user’s logon keychain. This may provide the adversary with various plaintext passwords, such as those for users, WiFi, mail, browsers, certificates, secure notes, etc.[2][3]

In OS X prior to El Capitan, users with root access can read plaintext keychain passwords of logged-in users because Apple’s keychain implementation allows these credentials to be cached so that users are not repeatedly prompted for passwords.[2][4] Apple’s `securityd` utility takes the user’s logon password, encrypts it with PBKDF2, and stores this master key in memory. Apple also uses a set of keys and algorithms to encrypt the user’s password, but once the master key is found, an adversary need only iterate over the other values to unlock the final password.[2]

Adversaries may buy, lease, rent, or obtain physical servers that can be used during targeting. Use of servers allows an adversary to stage, launch, and execute an operation. During post-compromise activity, adversaries may utilize servers for various tasks, such as watering hole operations in Drive-by Compromise, enabling Phishing operations, or facilitating Command and Control. Instead of compromising a third-party Server or renting a Virtual Private Server, adversaries may opt to configure and run their own servers in support of operations. Free trial periods of cloud servers may also be abused.[1][2]

Adversaries may only need a lightweight setup if most of their activities will take place using online infrastructure. Or, they may need to build extensive infrastructure if they want to test, communicate, and control other aspects of their activities on their own systems.[3]

Adversaries may compromise third-party servers that can be used during targeting. Use of servers allows an adversary to stage, launch, and execute an operation. During post-compromise activity, adversaries may utilize servers for various tasks, including for Command and Control.[1] Instead of purchasing a Server or Virtual Private Server, adversaries may compromise third-party servers in support of operations.

Adversaries may also compromise web servers to support watering hole operations, as in Drive-by Compromise, or email servers to support Phishing operations.

Adversaries may purchase and configure serverless cloud infrastructure, such as Cloudflare Workers, AWS Lambda functions, or Google Apps Scripts, that can be used during targeting. By utilizing serverless infrastructure, adversaries can make it more difficult to attribute infrastructure used during operations back to them.

Once acquired, the serverless runtime environment can be leveraged to either respond directly to infected machines or to Proxy traffic to an adversary-owned command and control server.[1][2][3] As traffic generated by these functions will appear to come from subdomains of common cloud providers, it may be difficult to distinguish from ordinary traffic to these providers - making it easier to Hide Infrastructure.[4][1]

Adversaries may compromise serverless cloud infrastructure, such as Cloudflare Workers, AWS Lambda functions, or Google Apps Scripts, that can be used during targeting. By utilizing serverless infrastructure, adversaries can make it more difficult to attribute infrastructure used during operations back to them.

Once compromised, the serverless runtime environment can be leveraged to either respond directly to infected machines or to Proxy traffic to an adversary-owned command and control server.[1][2][3] As traffic generated by these functions will appear to come from subdomains of common cloud providers, it may be difficult to distinguish from ordinary traffic to these providers - making it easier to Hide Infrastructure.[4][1]

Adversaries may abuse the Windows service control manager to execute malicious commands or payloads. The Windows service control manager (services.exe) is an interface to manage and manipulate services.[1] The service control manager is accessible to users via GUI components as well as system utilities such as sc.exe and Net.

PsExec can also be used to execute commands or payloads via a temporary Windows service created through the service control manager API.[2] Tools such as PsExec and sc.exe can accept remote servers as arguments and may be used to conduct remote execution.

Adversaries may leverage these mechanisms to execute malicious content. This can be done by either executing a new or modified service. This technique is the execution used in conjunction with Windows Service during service persistence or privilege escalation.