A WAR file is a Web Application Archive used to package and deploy Java web applications. In an attack, it can be abused as a delivery container for malicious code because the archive may include scripts or web shells that execute once the application is deployed on the server.
What a WAR file does in Java deployment
A WAR file is the packaging unit that lets a Java web application move from source code to a deployable archive. It bundles application classes, configuration, static assets, and supporting resources into a single artifact that an application server can unpack and run.
That packaging convenience is also why the format matters operationally: once a WAR is trusted and deployed, the server typically treats its contents as application material rather than as something to inspect file by file. The archive boundary therefore becomes part of the trust boundary.
Why WAR files are attractive for attackers
Attackers like WAR files because they can blend malicious functionality into a normal deployment workflow. A malicious archive may contain web shells, backdoor endpoints, startup hooks, or altered application classes that execute when the container deploys the application.
This is a delivery-container problem, not just a file-format problem. The abuse works because a web platform is designed to load and execute packaged code, so a compromised build, upload path, or artifact repository can turn a routine deployment into code execution on the server.
Exposure points across the build and deployment path
Exposure is usually easiest to assess by following the artifact lifecycle: who can create the WAR, who can upload or publish it, where it is stored, and which servers will accept it. Internet-facing upload features, CI/CD pipelines, artifact repositories, and admin consoles are common places where a malicious archive can enter the environment.
Once deployed, the artifact should be treated like executable software, not inert content. Integrity controls, provenance checks, and restricted deployment permissions help determine whether the WAR is a legitimate release or an attacker-supplied package. For broader hardening of deploy-time trust boundaries, NIST Cybersecurity Framework 2.0 is useful for mapping governance, protection, detection, and recovery around the deployment chain.
How defenders detect and limit misuse
Detection should look for the consequences of archive-based execution, not just the archive itself. Unusual new servlets, unexpected JSP files, unfamiliar administrative endpoints, changes in the webroot, and outbound connections from the application process can all indicate that a WAR has been abused after deployment.
Compromise review should also include the artifact source, because the deployed file may only be the visible symptom of a deeper supply-chain or access-control failure. When the subject is Java web delivery, MITRE ATT&CK Enterprise Matrix helps frame the post-exploitation behaviours that commonly follow initial web application execution.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
MITRE ATT&CK addresses the attack and risk surface, while NIST CSF 2.0, NIST SP 800-53 Rev 5, OWASP ASVS and CIS Controls v8 set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| NIST CSF 2.0 | PR.DS-08 — Integrity Verification | WAR files require integrity and provenance checks before deployment. |
| DE.CM-01 — Networks and network services are monitored to find potential cybersecurity events | Deployed WAR abuse is often detected through runtime and network anomalies. | |
| RC.RP-01 — Recovery is executed to restore systems or assets | Compromised WAR deployments require restoration of trusted application artifacts. | |
| Recommendation — Verify artifact integrity before deployment and reject untrusted WAR packages. Monitor application behavior and outbound connections for suspicious post-deploy activity. Restore the application from known-good artifacts after removing the malicious WAR. | ||
| NIST SP 800-53 Rev 5 | SI-7 — Software, Firmware, and Information Integrity | WAR archives are executable software artifacts whose integrity must be validated. |
| CM-5 — Access Restrictions for Change | Deployment authority over WAR files must be tightly restricted to prevent malicious publication. | |
| Recommendation — Validate software artifact integrity before deployment and flag tampered WAR files. Restrict who can publish or modify deployable WAR artifacts. | ||
| MITRE ATT&CK | T1505.003 — Web Shell | Malicious WAR files commonly deliver web shells or similar server-side code. |
| Recommendation — Hunt for server-side web shells and remove any malicious code embedded in deployed WARs. | ||
| OWASP ASVS | V15 — Secure Coding and Architecture | WAR packaging decisions affect how web application code is delivered and trusted. |
| Recommendation — Design deployment pipelines so packaged application code cannot be altered unnoticed. | ||
| CIS Controls v8 | CIS-16 — Application Software Security | WAR abuse is an application delivery and trust issue that benefits from secure release controls. |
| Recommendation — Apply secure release controls to prevent untrusted WAR artifacts from reaching production. | ||
Practitioner Guidance
Why practitioners should care: WAR files are both a deployment format and an execution vehicle, so the security question is not only whether the archive is valid, but whether its contents are trustworthy at the moment the server loads them. That makes provenance, upload control, and post-deploy monitoring part of the same control problem.
What to watch for: A WAR uploaded outside the normal release path, a sudden change in web application behavior, or a deployed archive that contains unexpected scripts or binaries should trigger immediate review of the artifact source and the runtime host.
Practitioner takeaway: Treat the WAR as a signed, governed release artifact, and treat any unsigned or out-of-band archive as a potential code-execution event until proven otherwise.
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Reviewed and updated by the NHIMG editorial team on October 31, 2026.
NHI Mgmt Group — the #1 independent authority on Non-Human Identity, IAM, and Agentic AI security. nhimg.org