Techniques

Adversaries may acquire information about vulnerabilities that can be used during targeting. A vulnerability is a weakness in computer hardware or software that can, potentially, be exploited by an adversary to cause unintended or unanticipated behavior to occur. Adversaries may find vulnerability information by searching open databases or gaining access to closed vulnerability databases.[1]

An adversary may monitor vulnerability disclosures/databases to understand the state of existing, as well as newly discovered, vulnerabilities. There is usually a delay between when a vulnerability is discovered and when it is made public. An adversary may target the systems of those known to conduct vulnerability research (including commercial vendors). Knowledge of a vulnerability may cause an adversary to search for an existing exploit (i.e. Exploits) or to attempt to develop one themselves (i.e. Exploits).

Adversaries may scan victims for vulnerabilities that can be used during targeting. Vulnerability scans typically check if the configuration of a target host/application (ex: software and version) potentially aligns with the target of a specific exploit the adversary may seek to use.

These scans may also include more broad attempts to Gather Victim Host Information that can be used to identify more commonly known, exploitable vulnerabilities. Vulnerability scans typically harvest running software and version numbers via server banners, listening ports, 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: Exploit Public-Facing Application).

Adversaries may search public WHOIS data for information about victims that can be used during targeting. WHOIS data is stored by regional Internet registries (RIR) responsible for allocating and assigning Internet resources such as domain names. Anyone can query WHOIS servers for information about a registered domain, such as assigned IP blocks, contact information, and DNS nameservers.[1]

Adversaries may search WHOIS data to gather actionable information. Threat actors can use online resources or command-line utilities to pillage through WHOIS data for information about potential victims. Information from these sources may reveal opportunities for other forms of reconnaissance (ex: Active Scanning or Phishing for Information), establishing operational resources (ex: Acquire Infrastructure or Compromise Infrastructure), and/or initial access (ex: External Remote Services or Trusted Relationship).

Adversaries may compromise a network device’s encryption capability in order to bypass encryption that would otherwise protect data communications.[1]

Encryption can be used to protect transmitted network traffic to maintain its confidentiality (protect against unauthorized disclosure) and integrity (protect against unauthorized changes). Encryption ciphers are used to convert a plaintext message to ciphertext and can be computationally intensive to decipher without the associated decryption key. Typically, longer keys increase the cost of cryptanalysis, or decryption without the key.

Adversaries can compromise and manipulate devices that perform encryption of network traffic. For example, through behaviors such as Modify System Image, Reduce Key Space, and Disable Crypto Hardware, an adversary can negatively effect and/or eliminate a device’s ability to securely encrypt network traffic. This poses a greater risk of unauthorized disclosure and may help facilitate data manipulation, Credential Access, or Collection efforts.[2]

Adversaries may forge web cookies that can be used to gain access to web applications or Internet services. Web applications and services (hosted in cloud SaaS environments or on-premise servers) often use session cookies to authenticate and authorize user access.

Adversaries may generate these cookies in order to gain access to web resources. This differs from Steal Web Session Cookie and other similar behaviors in that the cookies are new and forged by the adversary, rather than stolen or intercepted from legitimate users. Most common web applications have standardized and documented cookie values that can be generated using provided tools or interfaces.[1] The generation of web cookies often requires secret values, such as passwords, Private Keys, or other cryptographic seed values.

Once forged, adversaries may use these web cookies to access resources (Web Session Cookie), which may bypass multi-factor and other authentication protection mechanisms.[2][1][3]

Adversaries may install code on externally facing portals, such as a VPN login page, to capture and transmit credentials of users who attempt to log into the service. For example, a compromised login page may log provided user credentials before logging the user in to the service.

This variation on input capture may be conducted post-compromise using legitimate administrative access as a backup measure to maintain network access through External Remote Services and Valid Accounts or as part of the initial compromise by exploitation of the externally facing web service.[1]

Adversaries may communicate using application layer protocols associated with web traffic to avoid detection/network filtering by blending in with existing traffic. Commands to the remote system, and often the results of those commands, will be embedded within the protocol traffic between the client and server.

Protocols such as HTTP/S[1] and WebSocket[2] that carry web traffic may be very common in environments. HTTP/S packets have many fields and headers in which data can be concealed. An adversary may abuse these protocols to communicate with systems under their control within a victim network while also mimicking normal, expected traffic.

Adversaries may communicate using application layer protocols associated with web protocols traffic to avoid detection/network filtering by blending in with existing traffic. Commands to remote mobile devices, and often the results of those commands, will be embedded within the protocol traffic between the mobile client and server.

Web protocols such as HTTP and HTTPS are used for web traffic as well as well as notification services native to mobile messaging services such as Google Cloud Messaging (GCM) and newly, Firebase Cloud Messaging (FCM), (GCM/FCM: two-way communication) and Apple Push Notification Service (APNS; one-way server-to-device). Such notification services leverage HTTP/S via the respective API and are commonly abused on Android and iOS respectively in order blend in with routine device traffic making it difficult for enterprises to inspect.

Adversaries may use an existing, legitimate external Web service as a means for relaying data to/from a compromised system. Popular websites, cloud services, and social media acting as a mechanism for C2 may give a significant amount of cover due to the likelihood that hosts within a network are already communicating with them prior to a compromise. Using common services, such as those offered by Google, Microsoft, or Twitter, makes it easier for adversaries to hide in expected noise.[1] Web service providers commonly use SSL/TLS encryption, giving adversaries an added level of protection.

Use of Web services may also protect back-end C2 infrastructure from discovery through malware binary analysis while also enabling operational resiliency (since this infrastructure may be dynamically changed).

Adversaries may use an existing, legitimate external Web service as a means for relaying data to/from a compromised system. Popular websites and social media, acting as a mechanism for C2, may give a significant amount of cover. This is due to the likelihood that hosts within a network are already communicating with them prior to a compromise. Using common services, such as those offered by Google or Twitter, makes it easier for adversaries to hide in expected noise. Web service providers commonly use SSL/TLS encryption, giving adversaries an added level of protection.

Use of Web services may also protect back-end C2 infrastructure from discovery through malware binary analysis, or enable operational resiliency (since this infrastructure may be dynamically changed).

Adversaries may register for web services that can be used during targeting. A variety of popular websites exist for adversaries to register for a web-based service that can be abused during later stages of the adversary lifecycle, such as during Command and Control (Web Service), Exfiltration Over Web Service, or Phishing. Using common services, such as those offered by Google, GitHub, or Twitter, makes it easier for adversaries to hide in expected noise.[1][2] By utilizing a web service, adversaries can make it difficult to physically tie back operations to them.

Adversaries may compromise access to third-party web services that can be used during targeting. A variety of popular websites exist for legitimate users to register for web-based services, such as GitHub, Twitter, Dropbox, Google, SendGrid, etc. Adversaries may try to take ownership of a legitimate user's access to a web service and use that web service as infrastructure in support of cyber operations. Such web services can be abused during later stages of the adversary lifecycle, such as during Command and Control (Web Service), Exfiltration Over Web Service, or Phishing.[1] Using common services, such as those offered by Google or Twitter, makes it easier for adversaries to hide in expected noise. By utilizing a web service, particularly when access is stolen from legitimate users, adversaries can make it difficult to physically tie back operations to them. Additionally, leveraging compromised web-based email services may allow adversaries to leverage the trust associated with legitimate domains.

Adversaries can use stolen session cookies to authenticate to web applications and services. This technique bypasses some multi-factor authentication protocols since the session is already authenticated.[1]

Authentication cookies are commonly used in web applications, including cloud-based services, after a user has authenticated to the service so credentials are not passed and re-authentication does not need to occur as frequently. Cookies are often valid for an extended period of time, even if the web application is not actively used. After the cookie is obtained through Steal Web Session Cookie or Web Cookies, the adversary may then import the cookie into a browser they control and is then able to use the site or application as the user for as long as the session cookie is active. Once logged into the site, an adversary can access sensitive information, read email, or perform actions that the victim account has permissions to perform.

There have been examples of malware targeting session cookies to bypass multi-factor authentication systems.[2]

Adversaries can use stolen session cookies to authenticate to web applications and services. This technique bypasses some multi-factor authentication protocols since the session is already authenticated.[1]

Authentication cookies are commonly used in web applications, including cloud-based services, after a user has authenticated to the service so credentials are not passed and re-authentication does not need to occur as frequently. Cookies are often valid for an extended period of time, even if the web application is not actively used. After the cookie is obtained through Steal Web Session Cookie, the adversary then imports the cookie into a browser they control and is able to use the site or application as the user for as long as the session cookie is active. Once logged into the site, an adversary can access sensitive information, read email, or perform actions that the victim account has permissions to perform.

There have been examples of malware targeting session cookies to bypass multi-factor authentication systems.[2]

Adversaries may backdoor web servers with web shells to establish persistent access to systems. A Web shell is a Web script that is placed on an openly accessible Web server to allow an adversary to access the Web server as a gateway into a network. A Web shell may provide a set of functions to execute or a command-line interface on the system that hosts the Web server.[1]

In addition to a server-side script, a Web shell may have a client interface program that is used to talk to the Web server (e.g. China Chopper Web shell client).[2]

A Web shell is a Web script that is placed on an openly accessible Web server to allow an adversary to use the Web server as a gateway into a network. A Web shell may provide a set of functions to execute or a command-line interface on the system that hosts the Web server. In addition to a server-side script, a Web shell may have a client interface program that is used to talk to the Web server (see, for example, China Chopper Web shell client). [1]

Web shells may serve as Redundant Access or as a persistence mechanism in case an adversary's primary access methods are detected and removed.

Adversaries may block access to Wi-Fi communications to prevent messages from reaching target systems and devices. Wi-Fi connections allow for communications between IT and OT systems and devices. Blocking Wi-Fi communications may also block command and reporting messages.[1]

An adversary may block Wi-Fi communications by disabling network interfaces, Service Stop, conducting an Adversary-in-the-Middle attack and dropping the network traffic, or by jamming the Wi-Fi signal.

Adversaries may search for information about Wi-Fi networks, such as network names and passwords, on compromised systems. Adversaries may use Wi-Fi information as part of Account Discovery, Remote System Discovery, and other discovery or Credential Access activity to support both ongoing and future campaigns.

Adversaries may collect various types of information about Wi-Fi networks from hosts. For example, on Windows names and passwords of all Wi-Fi networks a device has previously connected to may be available through `netsh wlan show profiles` to enumerate Wi-Fi names and then `netsh wlan show profile “Wi-Fi name” key=clear` to show a Wi-Fi network’s corresponding password.[1][2][3] Additionally, names and other details of locally reachable Wi-Fi networks can be discovered using calls to `wlanAPI.dll` Native API functions.[4]

On Linux, names and passwords of all Wi-Fi-networks a device has previously connected to may be available in files under ` /etc/NetworkManager/system-connections/`.[5] On macOS, the password of a known Wi-Fi may be identified with ` security find-generic-password -wa wifiname` (requires admin username/password).[6]

Adversaries may search for information about Wi-Fi networks, such as network names and passwords, on compromised systems. Adversaries may use Wi-Fi information as part of Discovery or Credential Access activity to support both ongoing and future campaigns.

Adversaries may gain initial access to target systems by connecting to wireless networks. They may accomplish this by exploiting open Wi-Fi networks used by target devices or by accessing secured Wi-Fi networks — requiring Valid Accounts — belonging to a target organization.[1][2] Establishing a connection to a Wi-Fi access point requires a certain level of proximity to both discover and maintain a stable network connection.

Adversaries may establish a wireless connection through various methods, such as by physically positioning themselves near a Wi-Fi network to conduct close access operations. To bypass the need for physical proximity, adversaries may attempt to remotely compromise nearby third-party systems that have both wired and wireless network connections available (i.e., dual-homed systems). These third-party compromised devices can then serve as a bridge to connect to a target’s Wi-Fi network.[2]

Once an initial wireless connection is achieved, adversaries may leverage this access for follow-on activities in the victim network or further targeting of specific devices on the network. Adversaries may perform Network Sniffing or Adversary-in-the-Middle activities for Credential Access or Discovery.

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 server message block (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]

The Net utility can be used to connect to Windows admin shares on remote systems using net use commands with valid credentials. [4]

Adversaries may abuse the Windows command shell for execution. The Windows command shell (cmd) is the primary command prompt on Windows systems. The Windows command prompt can be used to control almost any aspect of a system, with various permission levels required for different subsets of commands. The command prompt can be invoked remotely via Remote Services such as SSH.[1]

Batch files (ex: .bat or .cmd) also provide the shell with a list of sequential commands to run, as well as normal scripting operations such as conditionals and loops. Common uses of batch files include long or repetitive tasks, or the need to run the same set of commands on multiple systems.

Adversaries may leverage cmd to execute various commands and payloads. Common uses include cmd to execute a single command, or abusing cmd interactively with input and output forwarded over a command and control channel.

Adversaries may acquire credentials from the Windows Credential Manager. The Credential Manager stores credentials for signing into websites, applications, and/or devices that request authentication through NTLM or Kerberos in Credential Lockers (previously known as Windows Vaults).[1][2]

The Windows Credential Manager separates website credentials from application or network credentials in two lockers. As part of Credentials from Web Browsers, Internet Explorer and Microsoft Edge website credentials are managed by the Credential Manager and are stored in the Web Credentials locker. Application and network credentials are stored in the Windows Credentials locker.

Credential Lockers store credentials in encrypted `.vcrd` files, located under `%Systemdrive%\Users\\[Username]\AppData\Local\Microsoft\\[Vault/Credentials]\`. The encryption key can be found in a file named Policy.vpol, typically located in the same folder as the credentials.[3][4]

Adversaries may list credentials managed by the Windows Credential Manager through several mechanisms. vaultcmd.exe is a native Windows executable that can be used to enumerate credentials stored in the Credential Locker through a command-line interface. Adversaries may also gather credentials by directly reading files located inside of the Credential Lockers. Windows APIs, such as CredEnumerateA, may also be absued to list credentials managed by the Credential Manager.[5][6]

Adversaries may also obtain credentials from credential backups. Credential backups and restorations may be performed by running rundll32.exe keymgr.dll KRShowKeyMgr then selecting the “Back up...” button on the “Stored User Names and Passwords” GUI.

Password recovery tools may also obtain plain text passwords from the Credential Manager.[4]

Adversaries may disable or modify the Windows host firewall to bypass controls limiting network usage. This can include disabling the Windows host firewall entirely, suppressing specific profiles (domain, private, public), or adding, deleting, and modifying firewall rules to allow or restrict traffic.[1]

Adversaries may perform these modifications through multiple mechanisms depending on the Windows operating system and access level. For example, adversaries may use command-line utilities (e.g., `netsh advfirewall` or PowerShell cmdlets like `Set-NetFirewallProfile`, `New-NetFirewallRule`), Windows Registry modifications (e.g., altering firewall states and rule configurations via registry keys), or the Windows Control Panel to modify firewall settings through the Windows Security interface.

By disabling or modifying Windows firewall services, adversaries may enable access to remote services, open ports for command and control traffic, or configure rules for further actions.

Adversaries may abuse Windows Management Instrumentation (WMI) to execute malicious commands and payloads. WMI is designed for programmers and is the infrastructure for management data and operations on Windows systems.[1] WMI is an administration feature that provides a uniform environment to access Windows system components.

The WMI service enables both local and remote access, though the latter is facilitated by Remote Services such as Distributed Component Object Model and Windows Remote Management.[1] Remote WMI over DCOM operates using port 135, whereas WMI over WinRM operates over port 5985 when using HTTP and 5986 for HTTPS.[1] [2]

An adversary can use WMI to interact with local and remote systems and use it as a means to execute various behaviors, such as gathering information for Discovery as well as Execution of commands and payloads.[2] For example, `wmic.exe` can be abused by an adversary to delete shadow copies with the command `wmic.exe Shadowcopy Delete` (i.e., Inhibit System Recovery).[3]

**Note:** `wmic.exe` is deprecated as of January of 2024, with the WMIC feature being “disabled by default” on Windows 11+. WMIC will be removed from subsequent Windows releases and replaced by PowerShell as the primary WMI interface.[4] In addition to PowerShell and tools like `wbemtool.exe`, COM APIs can also be used to programmatically interact with WMI via C++, .NET, VBScript, etc.[4]