Enterprise techniques

Adversaries may interact with the Windows Registry as part of a variety of other techniques to aid in defense evasion, persistence, and execution.

Access to specific areas of the Registry depends on account permissions, with some keys requiring administrator-level access. The built-in Windows command-line utility Reg may be used for local or remote Registry modification.[1] Other tools, such as remote access tools, may also contain functionality to interact with the Registry through the Windows API.

The Registry may be modified in order to hide configuration information or malicious payloads via Obfuscated Files or Information.[2][3][4][5] The Registry may also be modified to impair defenses, such as by enabling macros for all Microsoft Office products, allowing privilege escalation without alerting the user, increasing the maximum number of allowed outbound requests, and/or modifying systems to store plaintext credentials in memory.[6][2]

The Registry of a remote system may be modified to aid in execution of files as part of lateral movement. It requires the remote Registry service to be running on the target system.[7] Often Valid Accounts are required, along with access to the remote system's SMB/Windows Admin Shares for RPC communication.

Finally, Registry modifications may also include actions to hide keys, such as prepending key names with a null character, which will cause an error and/or be ignored when read via Reg or other utilities using the Win32 API.[8] Adversaries may abuse these pseudo-hidden keys to conceal payloads/commands used to maintain persistence.[9][10]

Adversaries may make changes to the operating system of embedded network devices to weaken defenses and provide new capabilities for themselves. On such devices, the operating systems are typically monolithic and most of the device functionality and capabilities are contained within a single file.

To change the operating system, the adversary typically only needs to affect this one file, replacing or modifying it. This can either be done live in memory during system runtime for immediate effect, or in storage to implement the change on the next boot of the network device.

Adversaries may target multi-factor authentication (MFA) mechanisms, (i.e., smart cards, token generators, etc.) to gain access to credentials that can be used to access systems, services, and network resources. Use of MFA is recommended and provides a higher level of security than usernames and passwords alone, but organizations should be aware of techniques that could be used to intercept and bypass these security mechanisms.

If a smart card is used for multi-factor authentication, then a keylogger will need to be used to obtain the password associated with a smart card during normal use. With both an inserted card and access to the smart card password, an adversary can connect to a network resource using the infected system to proxy the authentication with the inserted hardware token. [1]

Adversaries may also employ a keylogger to similarly target other hardware tokens, such as RSA SecurID. Capturing token input (including a user's personal identification code) may provide temporary access (i.e. replay the one-time passcode until the next value rollover) as well as possibly enabling adversaries to reliably predict future authentication values (given access to both the algorithm and any seed values used to generate appended temporary codes). [2]

Other methods of MFA may be intercepted and used by an adversary to authenticate. It is common for one-time codes to be sent via out-of-band communications (email, SMS). If the device and/or service is not secured, then it may be vulnerable to interception. Service providers can also be targeted: for example, an adversary may compromise an SMS messaging service in order to steal MFA codes sent to users’ phones.[3]

Adversaries may attempt to bypass multi-factor authentication (MFA) mechanisms and gain access to accounts by generating MFA requests sent to users.

Adversaries in possession of credentials to Valid Accounts may be unable to complete the login process if they lack access to the 2FA or MFA mechanisms required as an additional credential and security control. To circumvent this, adversaries may abuse the automatic generation of push notifications to MFA services such as Duo Push, Microsoft Authenticator, Okta, or similar services to have the user grant access to their account. If adversaries lack credentials to victim accounts, they may also abuse automatic push notification generation when this option is configured for self-service password reset (SSPR).[1]

In some cases, adversaries may continuously repeat login attempts in order to bombard users with MFA push notifications, SMS messages, and phone calls, potentially resulting in the user finally accepting the authentication request in response to “MFA fatigue.”[2][3][4]

Adversaries may create multiple stages for command and control that are employed under different conditions or for certain functions. Use of multiple stages may obfuscate the command and control channel to make detection more difficult.

Remote access tools will call back to the first-stage command and control server for instructions. The first stage may have automated capabilities to collect basic host information, update tools, and upload additional files. A second remote access tool (RAT) could be uploaded at that point to redirect the host to the second-stage command and control server. The second stage will likely be more fully featured and allow the adversary to interact with the system through a reverse shell and additional RAT features.

The different stages will likely be hosted separately with no overlapping infrastructure. The loader may also have backup first-stage callbacks or Fallback Channels in case the original first-stage communication path is discovered and blocked.

Adversaries may interact with the native OS application programming interface (API) to execute behaviors. Native APIs provide a controlled means of calling low-level OS services within the kernel, such as those involving hardware/devices, memory, and processes.[1][2] These native APIs are leveraged by the OS during system boot (when other system components are not yet initialized) as well as carrying out tasks and requests during routine operations.

Adversaries may abuse these OS API functions as a means of executing behaviors. Similar to Command and Scripting Interpreter, the native API and its hierarchy of interfaces provide mechanisms to interact with and utilize various components of a victimized system.

Native API functions (such as NtCreateProcess) may be directed invoked via system calls / syscalls, but these features are also often exposed to user-mode applications via interfaces and libraries.[3][4][5] For example, functions such as the Windows API CreateProcess() or GNU fork() will allow programs and scripts to start other processes.[6][7] This may allow API callers to execute a binary, run a CLI command, load modules, etc. as thousands of similar API functions exist for various system operations.[8][9][10]

Higher level software frameworks, such as Microsoft .NET and macOS Cocoa, are also available to interact with native APIs. These frameworks typically provide language wrappers/abstractions to API functionalities and are designed for ease-of-use/portability of code.[11][12][13][14]

Adversaries may use assembly to directly or in-directly invoke syscalls in an attempt to subvert defensive sensors and detection signatures such as user mode API-hooks.[15] Adversaries may also attempt to tamper with sensors and defensive tools associated with API monitoring, such as unhooking monitored functions via Disable or Modify Tools.

Adversaries may bridge network boundaries by compromising perimeter network devices or internal devices responsible for network segmentation. Breaching these devices may enable an adversary to bypass restrictions on traffic routing that otherwise separate trusted and untrusted networks.

Devices such as routers and firewalls can be used to create boundaries between trusted and untrusted networks. They achieve this by restricting traffic types to enforce organizational policy in an attempt to reduce the risk inherent in such connections. Restriction of traffic can be achieved by prohibiting IP addresses, layer 4 protocol ports, or through deep packet inspection to identify applications. To participate with the rest of the network, these devices can be directly addressable or transparent, but their mode of operation has no bearing on how the adversary can bypass them when compromised.

When an adversary takes control of such a boundary device, they can bypass its policy enforcement to pass normally prohibited traffic across the trust boundary between the two separated networks without hinderance. By achieving sufficient rights on the device, an adversary can reconfigure the device to allow the traffic they want, allowing them to then further achieve goals such as command and control via Multi-hop Proxy or exfiltration of data via Traffic Duplication. Adversaries may also target internal devices responsible for network segmentation and abuse these in conjunction with Internal Proxy to achieve the same goals.[1] In the cases where a border device separates two separate organizations, the adversary can also facilitate lateral movement into new victim environments.

Adversaries may perform Network Denial of Service (DoS) attacks to degrade or block the availability of targeted resources to users. Network DoS can be performed by exhausting the network bandwidth services rely on. Example resources include specific websites, email services, DNS, and web-based applications. Adversaries have been observed conducting network DoS attacks for political purposes[1] and to support other malicious activities, including distraction[2], hacktivism, and extortion.[3]

A Network DoS will occur when the bandwidth capacity of the network connection to a system is exhausted due to the volume of malicious traffic directed at the resource or the network connections and network devices the resource relies on. For example, an adversary may send 10Gbps of traffic to a server that is hosted by a network with a 1Gbps connection to the internet. This traffic can be generated by a single system or multiple systems spread across the internet, which is commonly referred to as a distributed DoS (DDoS).

To perform Network DoS attacks several aspects apply to multiple methods, including IP address spoofing, and botnets.

Adversaries may use the original IP address of an attacking system, or spoof the source IP address to make the attack traffic more difficult to trace back to the attacking system or to enable reflection. This can increase the difficulty defenders have in defending against the attack by reducing or eliminating the effectiveness of filtering by the source address on network defense devices.

For DoS attacks targeting the hosting system directly, see Endpoint Denial of Service.

Adversaries may attempt to get a listing of services running on remote hosts and local network infrastructure devices, including those that may be vulnerable to remote software exploitation. Common methods to acquire this information include port, vulnerability, and/or wordlist scans using tools that are brought onto a system.[1]

Within cloud environments, adversaries may attempt to discover services running on other cloud hosts. Additionally, if the cloud environment is connected to a on-premises environment, adversaries may be able to identify services running on non-cloud systems as well.

Within macOS environments, adversaries may use the native Bonjour application to discover services running on other macOS hosts within a network. The Bonjour mDNSResponder daemon automatically registers and advertises a host’s registered services on the network. For example, adversaries can use a mDNS query (such as dns-sd -B _ssh._tcp .) to find other systems broadcasting the ssh service.[2][3]

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. [1] [2] Net can be used to query a remote system for available shared drives using the net view \\\\remotesystem command. It can also be used to query shared drives on the local system using net share. For macOS, the sharing -l command lists all shared points used for smb services.

Adversaries may passively sniff network traffic to capture information about an environment, including authentication material passed over the network. Network sniffing refers to using the network interface on a system to monitor or capture information sent over a wired or wireless connection. An adversary may place a network interface into promiscuous mode to passively access data in transit over the network, or use span ports to capture a larger amount of data.

Data captured via this technique may include user credentials, especially those sent over an insecure, unencrypted protocol. Techniques for name service resolution poisoning, such as Name Resolution Poisoning and SMB Relay, can also be used to capture credentials to websites, proxies, and internal systems by redirecting traffic to an adversary.

Network sniffing may reveal configuration details, such as running services, version numbers, and other network characteristics (e.g. IP addresses, hostnames, VLAN IDs) necessary for subsequent Lateral Movement and/or Stealth activities. Adversaries may likely also utilize network sniffing during Adversary-in-the-Middle (AiTM) to passively gain additional knowledge about the environment.

In cloud-based environments, adversaries may still be able to use traffic mirroring services to sniff network traffic from virtual machines. For example, AWS Traffic Mirroring, GCP Packet Mirroring, and Azure vTap allow users to define specified instances to collect traffic from and specified targets to send collected traffic to.[1][2][3] Often, much of this traffic will be in cleartext due to the use of TLS termination at the load balancer level to reduce the strain of encrypting and decrypting traffic.[4][5] The adversary can then use exfiltration techniques such as Transfer Data to Cloud Account in order to access the sniffed traffic.[4]

On network devices, adversaries may perform network captures using Network Device CLI commands such as `monitor capture`.[6][7]

Adversaries may use an OSI non-application layer protocol for communication between host and C2 server or among infected hosts within a network. The list of possible protocols is extensive.[1] Specific examples include use of network layer protocols, such as the Internet Control Message Protocol (ICMP), transport layer protocols, such as the User Datagram Protocol (UDP), session layer protocols, such as Socket Secure (SOCKS), as well as redirected/tunneled protocols, such as Serial over LAN (SOL).

ICMP communication between hosts is one example.[2] Because ICMP is part of the Internet Protocol Suite, it is required to be implemented by all IP-compatible hosts.[3] However, it is not as commonly monitored as other Internet Protocols such as TCP or UDP and may be used by adversaries to hide communications.

In ESXi environments, adversaries may leverage the Virtual Machine Communication Interface (VMCI) for communication between guest virtual machines and the ESXi host. This traffic is similar to client-server communications on traditional network sockets but is localized to the physical machine running the ESXi host, meaning it does not traverse external networks (routers, switches). This results in communications that are invisible to external monitoring and standard networking tools like tcpdump, netstat, nmap, and Wireshark. By adding a VMCI backdoor to a compromised ESXi host, adversaries may persistently regain access from any guest VM to the compromised ESXi host’s backdoor, regardless of network segmentation or firewall rules in place.[4]

Adversaries may communicate using a protocol and port pairing that are typically not associated. For example, HTTPS over port 8088[1] or port 587[2] as opposed to the traditional port 443. Adversaries may make changes to the standard port used by a protocol to bypass filtering or muddle analysis/parsing of network data.

Adversaries may also make changes to victim systems to abuse non-standard ports. For example, Registry keys and other configuration settings can be used to modify protocol and port pairings.[3]

Adversaries may attempt to dump credentials to obtain account login and credential material, normally in the form of a hash or a clear text password. Credentials can be obtained from OS caches, memory, or structures.[1] Credentials can then be used to perform Lateral Movement and access restricted information.

Several of the tools mentioned in associated sub-techniques may be used by both adversaries and professional security testers. Additional custom tools likely exist as well.

Adversaries may attempt to make an executable or file difficult to discover or analyze by encrypting, encoding, or otherwise obfuscating its contents on the system or in transit. This is common behavior that can be used across different platforms and the network to evade defenses.

Payloads may be compressed, archived, or encrypted in order to avoid detection. These payloads may be used during Initial Access or later to mitigate detection. Sometimes a user's action may be required to open and Deobfuscate/Decode Files or Information for User Execution. The user may also be required to input a password to open a password protected compressed/encrypted file that was provided by the adversary.[1] Adversaries may also use compressed or archived scripts, such as JavaScript.

Portions of files can also be encoded to hide the plain-text strings that would otherwise help defenders with discovery.[2] Payloads may also be split into separate, seemingly benign files that only reveal malicious functionality when reassembled.[3]

Adversaries may also abuse Command Obfuscation to obscure commands executed from payloads or directly via Command and Scripting Interpreter. Environment variables, aliases, characters, and other platform/language specific semantics can be used to evade signature based detections and application control mechanisms.[4][5][6]

Adversaries may buy and/or steal capabilities that can be used during targeting. Rather than developing their own capabilities in-house, adversaries may purchase, freely download, or steal them. Activities may include the acquisition of malware, software (including licenses), exploits, certificates, and information relating to vulnerabilities. Adversaries may obtain capabilities to support their operations throughout numerous phases of the adversary lifecycle.

In addition to downloading free malware, software, and exploits from the internet, adversaries may purchase these capabilities from third-party entities. Third-party entities can include technology companies that specialize in malware and exploits, criminal marketplaces, or from individuals.[1][2]

In addition to purchasing capabilities, adversaries may steal capabilities from third-party entities (including other adversaries). This can include stealing software licenses, malware, SSL/TLS and code-signing certificates, or raiding closed databases of vulnerabilities or exploits.[3]

Adversaries may leverage Microsoft Office-based applications for persistence between startups. Microsoft Office is a fairly common application suite on Windows-based operating systems within an enterprise network. There are multiple mechanisms that can be used with Office for persistence when an Office-based application is started; this can include the use of Office Template Macros and add-ins.

A variety of features have been discovered in Outlook that can be abused to obtain persistence, such as Outlook rules, forms, and Home Page.[1] These persistence mechanisms can work within Outlook or be used through Office 365.[2]

Adversaries may attempt to access detailed information about the password policy used within an enterprise network or cloud environment. Password policies are a way to enforce complex passwords that are difficult to guess or crack through Brute Force. This information may help the adversary to create a list of common passwords and launch dictionary and/or brute force attacks which adheres to the policy (e.g. if the minimum password length should be 8, then not trying passwords such as 'pass123'; not checking for more than 3-4 passwords per account if the lockout is set to 6 as to not lock out accounts).

Password policies can be set and discovered on Windows, Linux, and macOS systems via various command shell utilities such as net accounts (/domain), Get-ADDefaultDomainPasswordPolicy, chage -l , cat /etc/pam.d/common-password, and pwpolicy getaccountpolicies [1] [2]. Adversaries may also leverage a Network Device CLI on network devices to discover password policy information (e.g. show aaa, show aaa common-criteria policy all).[3]

Password policies can be discovered in cloud environments using available APIs such as GetAccountPasswordPolicy in AWS [4].

Adversaries may attempt to gather information about attached peripheral devices and components connected to a computer system.[1][2] Peripheral devices could include auxiliary resources that support a variety of functionalities such as keyboards, printers, cameras, smart card readers, or removable storage. The information may be used to enhance their awareness of the system and network environment or may be used for further actions.

Adversaries may attempt to discover group and permission settings. This information can help adversaries determine which user accounts and groups are available, the membership of users in particular groups, and which users and groups have elevated permissions.

Adversaries may attempt to discover group permission settings in many different ways. This data may provide the adversary with information about the compromised environment that can be used in follow-on activity and targeting.[1]

Adversaries may send phishing messages to gain access to victim systems. All forms of phishing are electronically delivered social engineering. Phishing can be targeted, known as spearphishing. In spearphishing, a specific individual, company, or industry will be targeted by the adversary. More generally, adversaries can conduct non-targeted phishing, such as in mass malware spam campaigns.

Adversaries may send victims emails containing malicious attachments or links, typically to execute malicious code on victim systems. Phishing may also be conducted via third-party services, like social media platforms. Phishing may also involve social engineering techniques, such as posing as a trusted source, as well as evasive techniques such as removing or manipulating emails or metadata/headers from compromised accounts being abused to send messages (e.g., Email Hiding Rules).[1][2] Another way to accomplish this is by Email Spoofing[3] the identity of the sender, which can be used to fool both the human recipient as well as automated security tools,[4] or by including the intended target as a party to an existing email thread that includes malicious files or links (i.e., "thread hijacking").[5]

Victims may also receive phishing messages that instruct them to call a phone number where they are directed to visit a malicious URL, download malware,[6][7] or install adversary-accessible remote management tools onto their computer (i.e., User Execution).[8]

Adversaries may send phishing messages to elicit sensitive information that can be used during targeting. Phishing for information is an attempt to trick targets into divulging information, frequently credentials or other actionable information. Phishing for information is different from Phishing in that the objective is gathering data from the victim rather than executing malicious code.

All forms of phishing are electronically delivered social engineering. Phishing can be targeted, known as spearphishing. In spearphishing, a specific individual, company, or industry will be targeted by the adversary. More generally, adversaries can conduct non-targeted phishing, such as in mass credential harvesting campaigns.

Adversaries may also try to obtain information directly through the exchange of emails, instant messages, or other electronic conversation means.[1][2][3][4][5] Victims may also receive phishing messages that direct them to call a phone number where the adversary attempts to collect confidential information.[6]

Phishing for information frequently involves social engineering techniques, such as posing as a source with a reason to collect information (ex: Establish Accounts or Compromise Accounts) and/or sending multiple, seemingly urgent messages. Another way to accomplish this is by Email Spoofing[7] the identity of the sender, which can be used to fool both the human recipient as well as automated security tools.[8]

Phishing for information may also involve evasive techniques, such as removing or manipulating emails or metadata/headers from compromised accounts being abused to send messages (e.g., Email Hiding Rules).[9][10]

Adversaries may modify property list files (plist files) to enable other malicious activity, while also potentially evading and bypassing system defenses. macOS applications use plist files, such as the info.plist file, to store properties and configuration settings that inform the operating system how to handle the application at runtime. Plist files are structured metadata in key-value pairs formatted in XML based on Apple's Core Foundation DTD. Plist files can be saved in text or binary format.[1]

Adversaries can modify key-value pairs in plist files to influence system behaviors, such as hiding the execution of an application (i.e. Hidden Window) or running additional commands for persistence (ex: Launch Agent/Launch Daemon or Re-opened Applications).

For example, adversaries can add a malicious application path to the `~/Library/Preferences/com.apple.dock.plist` file, which controls apps that appear in the Dock. Adversaries can also modify the LSUIElement key in an application’s info.plist file to run the app in the background. Adversaries can also insert key-value pairs to insert environment variables, such as LSEnvironment, to enable persistence via Dynamic Linker Hijacking.[2][3]

Adversaries may impair a system's ability to hibernate, reboot, or shut down in order to extend access to infected machines. When a computer enters a dormant state, some or all software and hardware may cease to operate which can disrupt malicious activity.[1]

Adversaries may abuse system utilities and configuration settings to maintain access by preventing machines from entering a state, such as standby, that can terminate malicious activity.[2][3]

For example, `powercfg` controls all configurable power system settings on a Windows system and can be abused to prevent an infected host from locking or shutting down.[4] Adversaries may also extend system lock screen timeout settings.[5] Other relevant settings, such as disk and hibernate timeout, can be similarly abused to keep the infected machine running even if no user is active.[6]

Aware that some malware cannot survive system reboots, adversaries may entirely delete files used to invoke system shut down or reboot.[7]