Cavern

Valid accounts in cloud environments may allow adversaries to perform actions to achieve Initial Access, Persistence, Privilege Escalation, or Defense Evasion. Cloud accounts are those created and configured by an organization for use by users, remote support, services, or for administration of resources within a cloud service provider or SaaS application. Cloud Accounts can exist solely in the cloud; alternatively, they may be hybrid-joined between on-premises systems and the cloud through syncing or federation with other identity sources such as Windows Active Directory.

Evidence: 2026-07-21/hollowgraph-m365-calendar-graph-api-c2-cavern · ATT&CK page ↗

Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network. The weakness in the system can be a software bug, a temporary glitch, or a misconfiguration.

Evidence: 2026-07-12/weekly-w28-threat-actor-developments · ATT&CK page ↗

Adversaries may use voice communications to ultimately gain access to victim systems. Spearphishing voice is a specific variant of spearphishing. It is different from other forms of spearphishing in that it employs the use of manipulating a user into providing access to systems through a phone call or other forms of voice communications. Spearphishing frequently involves social engineering techniques, such as posing as a trusted source (ex: Impersonation) and/or creating a sense of urgency or alarm for the recipient.

Evidence: 2026-07-12/weekly-w28-threat-actor-developments · ATT&CK page ↗

Adversaries may abuse dynamic-link library files (DLLs) in order to achieve persistence, escalate privileges, and evade defenses. DLLs are libraries that contain code and data that can be simultaneously utilized by multiple programs. While DLLs are not malicious by nature, they can be abused through mechanisms such as side-loading, hijacking search order, and phantom DLL hijacking.

Evidence: 2026-07-09/cavern-manticore-iran-mois-modular-net-c2-anti-analysis · ATT&CK page ↗

Valid accounts in cloud environments may allow adversaries to perform actions to achieve Initial Access, Persistence, Privilege Escalation, or Defense Evasion. Cloud accounts are those created and configured by an organization for use by users, remote support, services, or for administration of resources within a cloud service provider or SaaS application. Cloud Accounts can exist solely in the cloud; alternatively, they may be hybrid-joined between on-premises systems and the cloud through syncing or federation with other identity sources such as Windows Active Directory.

Evidence: 2026-07-21/hollowgraph-m365-calendar-graph-api-c2-cavern · ATT&CK page ↗

Adversaries may inject malicious code into suspended and hollowed processes in order to evade process-based defenses. Process hollowing is a method of executing arbitrary code in the address space of a separate live process.

Evidence: 2026-07-26/weekly-w30-c2-through-trusted-infrastructure · ATT&CK page ↗

Valid accounts in cloud environments may allow adversaries to perform actions to achieve Initial Access, Persistence, Privilege Escalation, or Defense Evasion. Cloud accounts are those created and configured by an organization for use by users, remote support, services, or for administration of resources within a cloud service provider or SaaS application. Cloud Accounts can exist solely in the cloud; alternatively, they may be hybrid-joined between on-premises systems and the cloud through syncing or federation with other identity sources such as Windows Active Directory.

Evidence: 2026-07-21/hollowgraph-m365-calendar-graph-api-c2-cavern · ATT&CK page ↗

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.

Evidence: 2026-08-12/project-cav3rn-google-apps-script-c2-relay · 2026-07-21/hollowgraph-m365-calendar-graph-api-c2-cavern · 2026-07-09/cavern-manticore-iran-mois-modular-net-c2-anti-analysis · ATT&CK page ↗

Adversaries may match or approximate the name or location of legitimate files, Registry keys, or other resources when naming/placing them. This is done for the sake of evading defenses and observation.

Evidence: 2026-08-12/project-cav3rn-google-apps-script-c2-relay · ATT&CK page ↗

Adversaries may inject malicious code into suspended and hollowed processes in order to evade process-based defenses. Process hollowing is a method of executing arbitrary code in the address space of a separate live process.

Evidence: 2026-07-26/weekly-w30-c2-through-trusted-infrastructure · ATT&CK page ↗

Valid accounts in cloud environments may allow adversaries to perform actions to achieve Initial Access, Persistence, Privilege Escalation, or Defense Evasion. Cloud accounts are those created and configured by an organization for use by users, remote support, services, or for administration of resources within a cloud service provider or SaaS application. Cloud Accounts can exist solely in the cloud; alternatively, they may be hybrid-joined between on-premises systems and the cloud through syncing or federation with other identity sources such as Windows Active Directory.

Evidence: 2026-07-21/hollowgraph-m365-calendar-graph-api-c2-cavern · ATT&CK page ↗

Adversaries may abuse dynamic-link library files (DLLs) in order to achieve persistence, escalate privileges, and evade defenses. DLLs are libraries that contain code and data that can be simultaneously utilized by multiple programs. While DLLs are not malicious by nature, they can be abused through mechanisms such as side-loading, hijacking search order, and phantom DLL hijacking.

Evidence: 2026-07-09/cavern-manticore-iran-mois-modular-net-c2-anti-analysis · ATT&CK page ↗

Adversaries may reflectively load code into a process in order to conceal the execution of malicious payloads. Reflective loading involves allocating then executing payloads directly within the memory of the process, vice creating a thread or process backed by a file path on disk (e.g., Shared Modules).

Evidence: 2026-07-09/cavern-manticore-iran-mois-modular-net-c2-anti-analysis · ATT&CK page ↗

Adversaries may impersonate a trusted person or organization in order to persuade and trick a target into performing some action on their behalf. For example, adversaries may communicate with victims (via Phishing for Information, Phishing, or Internal Spearphishing) while impersonating a known sender such as an executive, colleague, or third-party vendor. Established trust can then be leveraged to accomplish an adversary’s ultimate goals, possibly against multiple victims.

Evidence: 2026-07-12/weekly-w28-threat-actor-developments · ATT&CK page ↗

Adversaries may disable, degrade, or tamper with security tools or applications (e.g., endpoint detection and response (EDR) tools, intrusion detection systems (IDS), antivirus, logging agents, sensors, etc.) to impair or reduce visibility of defensive capabilities. This may include stopping specific services, killing processes, modifying or deleting tool configuration files and Registry keys, or preventing tools from updating. This may also include impairing defenses more broadly by disrupting preventative, detection, and response mechanisms across host, network, and cloud environments.

Evidence: 2026-07-26/weekly-w30-c2-through-trusted-infrastructure · ATT&CK page ↗

Adversaries may use fallback or alternate communication channels if the primary channel is compromised or inaccessible in order to maintain reliable command and control and to avoid data transfer thresholds.

Evidence: 2026-07-22/cavern-cav3rn-oilrig-attribution-dns-aaaa-c2-fallback · ATT&CK page ↗

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.

Evidence: 2026-07-26/weekly-w30-c2-through-trusted-infrastructure · ATT&CK page ↗

Adversaries may communicate using the Domain Name System (DNS) application layer protocol 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.

Evidence: 2026-08-12/project-cav3rn-google-apps-script-c2-relay · 2026-07-26/weekly-w30-c2-through-trusted-infrastructure · 2026-07-22/cavern-cav3rn-oilrig-attribution-dns-aaaa-c2-fallback · 2026-07-21/hollowgraph-m365-calendar-graph-api-c2-cavern · ATT&CK page ↗

Adversaries may use a connection proxy to direct network traffic between systems or act as an intermediary for network communications to a command and control server to avoid direct connections to their infrastructure. Many tools exist that enable traffic redirection through proxies or port redirection, including HTRAN, ZXProxy, and ZXPortMap. Adversaries use these types of proxies to manage command and control communications, reduce the number of simultaneous outbound network connections, provide resiliency in the face of connection loss, or to ride over existing trusted communications paths between victims to avoid suspicion. Adversaries may chain together multiple proxies to further disguise the source of malicious traffic.

Evidence: 2026-07-26/weekly-w30-c2-through-trusted-infrastructure · ATT&CK page ↗

Adversaries may use an existing, legitimate external Web service as a means for sending commands to and receiving output from a compromised system over the Web service channel. Compromised systems may leverage popular websites and social media to host command and control (C2) instructions. Those infected systems can then send the output from those commands back over that Web service channel. The return traffic may occur in a variety of ways, depending on the Web service being utilized. For example, the return traffic may take the form of the compromised system posting a comment on a forum, issuing a pull request to development project, updating a document hosted on a Web service, or by sending a Tweet.

Evidence: 2026-08-12/project-cav3rn-google-apps-script-c2-relay · 2026-07-26/weekly-w30-c2-through-trusted-infrastructure · 2026-07-22/cavern-cav3rn-oilrig-attribution-dns-aaaa-c2-fallback · 2026-07-21/hollowgraph-m365-calendar-graph-api-c2-cavern · ATT&CK page ↗

Adversaries may transfer tools or other files from an external system into a compromised environment. Tools or files may be copied from an external adversary-controlled system to the victim network through the command and control channel or through alternate protocols such as ftp. Once present, adversaries may also transfer/spread tools between victim devices within a compromised environment (i.e. Lateral Tool Transfer).

Evidence: 2026-08-12/project-cav3rn-google-apps-script-c2-relay · ATT&CK page ↗

An adversary may use legitimate remote access tools to establish an interactive command and control channel within a network. Remote access tools create a session between two trusted hosts through a graphical interface, a command line interaction, a protocol tunnel via development or management software, or hardware-level access such as KVM (Keyboard, Video, Mouse) over IP solutions. Desktop support software (usually graphical interface) and remote management software (typically command line interface) allow a user to control a computer remotely as if they are a local user inheriting the user or software permissions. This software is commonly used for troubleshooting, software installation, and system management. Adversaries may similarly abuse response features included in EDR and other defensive tools that enable remote access.

Evidence: 2026-07-09/cavern-manticore-iran-mois-modular-net-c2-anti-analysis · ATT&CK page ↗

Adversaries may dynamically establish connections to command and control infrastructure to evade common detections and remediations. This may be achieved by using malware that shares a common algorithm with the infrastructure the adversary uses to receive the malware's communications. These calculations can be used to dynamically adjust parameters such as the domain name, IP address, or port number the malware uses for command and control.

Evidence: 2026-08-12/project-cav3rn-google-apps-script-c2-relay · ATT&CK page ↗

Adversaries may employ an encryption algorithm to conceal command and control traffic rather than relying on any inherent protections provided by a communication protocol. Despite the use of a secure algorithm, these implementations may be vulnerable to reverse engineering if secret keys are encoded and/or generated within malware samples/configuration files.

Evidence: 2026-07-22/cavern-cav3rn-oilrig-attribution-dns-aaaa-c2-fallback · 2026-07-21/hollowgraph-m365-calendar-graph-api-c2-cavern · ATT&CK page ↗

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.

Evidence: 2026-07-26/weekly-w30-c2-through-trusted-infrastructure · ATT&CK page ↗