Infection Monkey

Infection Monkey is an open-source breach-and-attack simulation tool for organizations assessing internal network resilience. It is a strong fit for teams that can operate their own deployment and want to trace potential routes through systems, rather than buy a commercial testing service.

Its value is the combination of agent-based simulation, network mapping, and security reporting at no cost. The trade-off is a specific deployment requirement: Monkey Island runs on x86-64 hardware with Linux or Windows.

Overview

The tool has two parts: Monkey Agent scans and simulates attack techniques, while Monkey Island serves as the command-and-control web interface. The resulting map connects visible machines, accessible services, and possible propagation routes. A report summarizes security issues the agents discover or exploit, giving teams a way to consider how separate exposures may combine into a route through the network.

Infection Monkey is intended to help organizations validate security controls and identify potential gaps. Its FAQ says it avoids exploits or attacks that may affect victim systems, including EternalBlue. That makes it better suited to controlled resilience assessments than to destructive testing.

Key features

Agent-based simulation and mapping

Agents scan and simulate attack techniques across local networks, internal servers, on-premises data centers, and cloud-based data centers. The map shows the machines and services they can see and the propagation routes they identify. This is useful for teams investigating how access might extend beyond an initial boundary; it is not a substitute for assessing systems outside the tool’s visible reach.

Security reporting and plugins

The report collects security issues discovered or exploited during agent activity, helping teams focus follow-up on potential control gaps. Plugins can extend the tool and can be installed, updated, removed, or uploaded through the Monkey Island interface. Organizations with custom attack scenarios can use that flexibility to tailor simulations, though plugin management and deployment remain part of their operational work.

Deployment and safeguards

Supported environments include on-premises systems, containers, and public and private clouds. An AWS integration uses Systems Manager to run Infection Monkey on EC2 instances. Internet access is not required; when present, it is used to check for updates and whether machines can reach the internet.

On first launch, users create credentials, and the Monkey Island server is then accessible only with those credentials. Sensitive data such as passwords, SSH keys, and hashes is stored encrypted in the Island database and sent to agents over HTTPS. These protections matter for a tool that handles credentials, but they do not remove the need to secure and manage the server yourself.

Pricing

Infection Monkey is free and open source. The Free plan costs nothing and includes the breach-and-attack simulation tool. There is no paid tier or trial to weigh against it, which makes it accessible to organizations able to self-host; buyers seeking a commercial subscription or managed service should consider other products.

Platforms

The product is listed for Linux, Windows, web, and self-hosted use. The documented Monkey Island server requires an x86-64 processor and supports Linux and Windows. Teams should account for those requirements before choosing a deployment; an environment that cannot run the server on that hardware and operating system combination is not a fit.

Who it's for

Infection Monkey suits security teams and organizations that want to validate controls, examine internal exposure, and understand possible routes between networked systems. Its hybrid deployment model and support for on-premises, container, and cloud environments make it relevant to varied infrastructure, while its self-hosted architecture favors teams able to manage their own installation. Support is available through a public Slack workspace, email, and GitHub issue reporting.

It is less appropriate for teams that need a managed assessment service, commercial subscription, or a server platform outside the documented x86-64 Linux and Windows requirements.

Pros and cons

• Free and open source: organizations can use the simulation tool without a subscription charge.
• Useful network-level context: maps connect visible machines and services to potential propagation routes, with reports summarizing agent findings.
• Flexible environments: supports on-premises, container, and public or private cloud environments, with an AWS Systems Manager integration for EC2.
• Deployment responsibility: Monkey Island is self-hosted, so teams need to manage the server and its credentials.
• Specific server requirements: the documented deployment requires x86-64 hardware and Linux or Windows, ruling out incompatible environments.

Alternatives

Atomic Red Team is another free, open-source option, with tests designed to run in five minutes or less and minimal setup; choose it when quick, lightweight tests matter more than Infection Monkey’s network map and propagation-route view.

MITRE Caldera is a free, open-source cybersecurity framework available across API, Linux, self-hosted, and web platforms. It may suit teams looking for a framework rather than Infection Monkey’s focused breach-and-attack simulation tool.

OpenAEV offers a free Community Edition billed free forever, with on-premises core attack simulation, tabletop exercises, and community support. Consider it if tabletop exercises are also a priority.

AttackIQ Platform has a free tier with access to Free Testing Packages and Adversary Research, plus a pay-as-you-go plan at $300, paid once. It is an option for readers seeking those packages and research rather than a self-hosted open-source tool.

FourCore ATTACK is another alternative in the paid category.

Keysight Eggplant Test is a paid alternative with a free trial and enterprise software sold by quote.

Stratus Red Team is a free alternative available across API, Linux, macOS, self-hosted, and Windows platforms.

Pentera Platform is a paid alternative with custom pricing.

Browse more options in Breach and Attack Simulation Software.

Verdict

Choose Infection Monkey if your organization wants a free, open-source way to simulate attack techniques and see potential routes through supported environments. Its map and security report provide practical context for reviewing control gaps. Look elsewhere if you need a managed or commercial service, or cannot run Monkey Island on x86-64 Linux or Windows.