Mozilla Firefox

Adversaries may gain access to a system through a user visiting a website over the normal course of browsing. Multiple ways of delivering exploit code to a browser exist (i.e., Drive-by Target), including:

Evidence: 2026-08-16/jewelbug-pdf-viewer-extension-native-messaging-webmail-hole · 2026-07-17/firefox-152-0-6-wasm-site-isolation-public-exploit · ATT&CK page ↗

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. 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.

Evidence: 2026-09-24/closedquorum-llm-orchestrated-c2-implant · ATT&CK page ↗

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.

Evidence: 2026-08-16/jewelbug-pdf-viewer-extension-native-messaging-webmail-hole · ATT&CK page ↗

Adversaries may abuse various implementations of JavaScript for execution. JavaScript (JS) is a platform-independent scripting language (compiled just-in-time at runtime) commonly associated with scripts in webpages, though JS can be executed in runtime environments outside the browser.

Evidence: 2026-07-28/medusahvnc-hidden-desktop-browser-session-hijacking · ATT&CK page ↗

Adversaries may exploit software vulnerabilities in client applications to execute code. Vulnerabilities can exist in software due to unsecure coding practices that can lead to unanticipated behavior. Adversaries can take advantage of certain vulnerabilities through targeted exploitation for the purpose of arbitrary code execution. Oftentimes the most valuable exploits to an offensive toolkit are those that can be used to obtain code execution on a remote system because they can be used to gain access to that system. Users will expect to see files related to the applications they commonly used to do work, so they are a useful target for exploit research and development because of their high utility.

Evidence: 2026-07-17/firefox-152-0-6-wasm-site-isolation-public-exploit · ATT&CK page ↗

An adversary may rely upon a user opening a malicious file in order to gain execution. Users may be subjected to social engineering to get them to open a file that will lead to code execution. This user action will typically be observed as follow-on behavior from Spearphishing Attachment. Adversaries may use several types of files that require a user to execute them, including .doc, .pdf, .xls, .rtf, .scr, .exe, .lnk, .pif, .cpl, .reg, and .iso.

Evidence: 2026-08-16/jewelbug-pdf-viewer-extension-native-messaging-webmail-hole · ATT&CK page ↗

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. 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.

Evidence: 2026-09-24/closedquorum-llm-orchestrated-c2-implant · ATT&CK page ↗

Adversaries may abuse internet browser extensions to establish persistent access to victim systems. Browser extensions or plugins are small programs that can add functionality to and customize aspects of internet browsers. They can be installed directly via a local file or custom URL or through a browser's app store - an official online platform where users can browse, install, and manage extensions for a specific web browser. Extensions generally inherit the web browser's permissions previously granted.

Evidence: 2026-08-16/jewelbug-pdf-viewer-extension-native-messaging-webmail-hole · ATT&CK page ↗

Adversaries may establish persistence and elevate privileges by executing malicious content triggered by a Windows Management Instrumentation (WMI) event subscription. WMI can be used to install event filters, providers, consumers, and bindings that execute code when a defined event occurs. Examples of events that may be subscribed to are the wall clock time, user login, or the computer's uptime.

Evidence: 2026-09-24/closedquorum-llm-orchestrated-c2-implant · ATT&CK page ↗

Adversaries may achieve persistence by adding a program to a startup folder or referencing it with a Registry run key. Adding an entry to the "run keys" in the Registry or startup folder will cause the program referenced to be executed when a user logs in. These programs will be executed under the context of the user and will have the account's associated permissions level.

Evidence: 2026-09-24/closedquorum-llm-orchestrated-c2-implant · 2026-07-28/medusahvnc-hidden-desktop-browser-session-hijacking · ATT&CK page ↗

Adversaries may modify pluggable authentication modules (PAM) to access user credentials or enable otherwise unwarranted access to accounts. PAM is a modular system of configuration files, libraries, and executable files which guide authentication for many services. The most common authentication module is <code>pam_unix.so</code>, which retrieves, sets, and verifies account authentication information in <code>/etc/passwd</code> and <code>/etc/shadow</code>.

Evidence: 2026-08-16/jewelbug-pdf-viewer-extension-native-messaging-webmail-hole · ATT&CK page ↗

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. 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.

Evidence: 2026-09-24/closedquorum-llm-orchestrated-c2-implant · ATT&CK page ↗

Adversaries may inject code into processes in order to evade process-based defenses as well as possibly elevate privileges. Process injection is a method of executing arbitrary code in the address space of a separate live process. Running code in the context of another process may allow access to the process's memory, system/network resources, and possibly elevated privileges. Execution via process injection may also evade detection from security products since the execution is masked under a legitimate process.

Evidence: 2026-07-28/medusahvnc-hidden-desktop-browser-session-hijacking · ATT&CK page ↗

Adversaries may inject malicious code into processes via the asynchronous procedure call (APC) queue in order to evade process-based defenses as well as possibly elevate privileges. APC injection is a method of executing arbitrary code in the address space of a separate live process.

Evidence: 2026-09-24/closedquorum-llm-orchestrated-c2-implant · 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: 2026-09-24/closedquorum-llm-orchestrated-c2-implant · ATT&CK page ↗

Adversaries may establish persistence and elevate privileges by executing malicious content triggered by a Windows Management Instrumentation (WMI) event subscription. WMI can be used to install event filters, providers, consumers, and bindings that execute code when a defined event occurs. Examples of events that may be subscribed to are the wall clock time, user login, or the computer's uptime.

Evidence: 2026-09-24/closedquorum-llm-orchestrated-c2-implant · ATT&CK page ↗

Adversaries may achieve persistence by adding a program to a startup folder or referencing it with a Registry run key. Adding an entry to the "run keys" in the Registry or startup folder will cause the program referenced to be executed when a user logs in. These programs will be executed under the context of the user and will have the account's associated permissions level.

Evidence: 2026-09-24/closedquorum-llm-orchestrated-c2-implant · 2026-07-28/medusahvnc-hidden-desktop-browser-session-hijacking · ATT&CK page ↗

Adversaries may use rootkits to hide the presence of programs, files, network connections, services, drivers, and other system components. Rootkits are programs that hide the existence of malware by intercepting/hooking and modifying operating system API calls that supply system information.

Evidence: 2026-08-16/jewelbug-pdf-viewer-extension-native-messaging-webmail-hole · ATT&CK page ↗

Adversaries may inject code into processes in order to evade process-based defenses as well as possibly elevate privileges. Process injection is a method of executing arbitrary code in the address space of a separate live process. Running code in the context of another process may allow access to the process's memory, system/network resources, and possibly elevated privileges. Execution via process injection may also evade detection from security products since the execution is masked under a legitimate process.

Evidence: 2026-07-28/medusahvnc-hidden-desktop-browser-session-hijacking · ATT&CK page ↗

Adversaries may inject malicious code into processes via the asynchronous procedure call (APC) queue in order to evade process-based defenses as well as possibly elevate privileges. APC injection is a method of executing arbitrary code in the address space of a separate live process.

Evidence: 2026-09-24/closedquorum-llm-orchestrated-c2-implant · 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: 2026-09-24/closedquorum-llm-orchestrated-c2-implant · ATT&CK page ↗

Adversaries may use Obfuscated Files or Information to hide artifacts of an intrusion from analysis. They may require separate mechanisms to decode or deobfuscate that information depending on how they intend to use it. Methods for doing that include built-in functionality of malware or by using utilities present on the system.

Evidence: 2026-07-28/medusahvnc-hidden-desktop-browser-session-hijacking · ATT&CK page ↗

Adversaries may employ various time-based methods to detect virtualization and analysis environments, particularly those that attempt to manipulate time mechanisms to simulate longer elapses of time. This may include enumerating time-based properties, such as uptime or the system clock.

Evidence: 2026-09-24/closedquorum-llm-orchestrated-c2-implant · ATT&CK page ↗

Adversaries may use hidden windows to conceal malicious activity from the plain sight of users. In some cases, windows that would typically be displayed when an application carries out an operation can be hidden. This may be utilized by system administrators to avoid disrupting user work environments when carrying out administrative tasks.

Evidence: 2026-07-28/medusahvnc-hidden-desktop-browser-session-hijacking · ATT&CK page ↗

Adversaries may modify pluggable authentication modules (PAM) to access user credentials or enable otherwise unwarranted access to accounts. PAM is a modular system of configuration files, libraries, and executable files which guide authentication for many services. The most common authentication module is <code>pam_unix.so</code>, which retrieves, sets, and verifies account authentication information in <code>/etc/passwd</code> and <code>/etc/shadow</code>.

Evidence: 2026-08-16/jewelbug-pdf-viewer-extension-native-messaging-webmail-hole · 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: 2026-09-24/closedquorum-llm-orchestrated-c2-implant · 2026-07-28/medusahvnc-hidden-desktop-browser-session-hijacking · ATT&CK page ↗

Adversaries may attempt to access credential material stored in the process memory of the Local Security Authority Subsystem Service (LSASS). After a user logs on, the system generates and stores a variety of credential materials in LSASS process memory. These credential materials can be harvested by an administrative user or SYSTEM and used to conduct Lateral Movement using Use Alternate Authentication Material.

Evidence: 2026-09-24/closedquorum-llm-orchestrated-c2-implant · ATT&CK page ↗

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.

Evidence: 2026-08-16/jewelbug-pdf-viewer-extension-native-messaging-webmail-hole · ATT&CK page ↗

An adversary may steal web application or service session cookies and use them to gain access to web applications or Internet services as an authenticated user without needing credentials. Web applications and services often use session cookies as an authentication token after a user has authenticated to a website.

Evidence: 2026-08-16/jewelbug-pdf-viewer-extension-native-messaging-webmail-hole · 2026-07-28/medusahvnc-hidden-desktop-browser-session-hijacking · ATT&CK page ↗

Adversaries may acquire credentials from web browsers by reading files specific to the target browser. Web browsers commonly save credentials such as website usernames and passwords so that they do not need to be entered manually in the future. Web browsers typically store the credentials in an encrypted format within a credential store; however, methods exist to extract plaintext credentials from web browsers.

Evidence: 2026-09-24/closedquorum-llm-orchestrated-c2-implant · 2026-07-28/medusahvnc-hidden-desktop-browser-session-hijacking · ATT&CK page ↗

Adversaries may modify pluggable authentication modules (PAM) to access user credentials or enable otherwise unwarranted access to accounts. PAM is a modular system of configuration files, libraries, and executable files which guide authentication for many services. The most common authentication module is <code>pam_unix.so</code>, which retrieves, sets, and verifies account authentication information in <code>/etc/passwd</code> and <code>/etc/shadow</code>.

Evidence: 2026-08-16/jewelbug-pdf-viewer-extension-native-messaging-webmail-hole · ATT&CK page ↗

Adversaries may employ various time-based methods to detect virtualization and analysis environments, particularly those that attempt to manipulate time mechanisms to simulate longer elapses of time. This may include enumerating time-based properties, such as uptime or the system clock.

Evidence: 2026-09-24/closedquorum-llm-orchestrated-c2-implant · ATT&CK page ↗

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.

Evidence: 2026-08-16/jewelbug-pdf-viewer-extension-native-messaging-webmail-hole · ATT&CK page ↗

Adversaries may attempt to take screen captures of the desktop to gather information over the course of an operation. Screen capturing functionality may be included as a feature of a remote access tool used in post-compromise operations. Taking a screenshot is also typically possible through native utilities or API calls, such as <code>CopyFromScreen</code>, <code>xwd</code>, or <code>screencapture</code>.

Evidence: 2026-08-16/jewelbug-pdf-viewer-extension-native-messaging-webmail-hole · ATT&CK page ↗

Adversaries may collect data stored in the clipboard from users copying information within or between applications.

Evidence: 2026-08-16/jewelbug-pdf-viewer-extension-native-messaging-webmail-hole · 2026-07-28/medusahvnc-hidden-desktop-browser-session-hijacking · ATT&CK page ↗

Adversaries may take advantage of security vulnerabilities and inherent functionality in browser software to change content, modify user-behaviors, and intercept information as part of various browser session hijacking techniques.

Evidence: 2026-08-16/jewelbug-pdf-viewer-extension-native-messaging-webmail-hole · 2026-07-28/medusahvnc-hidden-desktop-browser-session-hijacking · 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: 2026-08-16/jewelbug-pdf-viewer-extension-native-messaging-webmail-hole · ATT&CK page ↗

Adversaries may use an existing, legitimate external Web service to host information that points to additional command and control (C2) infrastructure. Adversaries may post content, known as a dead drop resolver, on Web services with embedded (and often obfuscated/encoded) domains or IP addresses. Once infected, victims will reach out to and be redirected by these resolvers.

Evidence: 2026-08-16/jewelbug-pdf-viewer-extension-native-messaging-webmail-hole · 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: 2026-09-24/closedquorum-llm-orchestrated-c2-implant · 2026-08-16/jewelbug-pdf-viewer-extension-native-messaging-webmail-hole · ATT&CK page ↗

Adversaries may exfiltrate data to a webhook endpoint rather than over their primary command and control channel. Webhooks are simple mechanisms for allowing a server to push data over HTTP/S to a client without the need for the client to continuously poll the server. Many public and commercial services, such as Discord, Slack, and `webhook.site`, support the creation of webhook endpoints that can be used by other services, such as Github, Jira, or Trello. When changes happen in the linked services (such as pushing a repository update or modifying a ticket), these services will automatically post the data to the webhook endpoint for use by the consuming application.

Evidence: 2026-09-24/closedquorum-llm-orchestrated-c2-implant · ATT&CK page ↗