THE KEY ANSWER
Prompt injection involves influencing model behavior through content that should be treated as data. Protection requires limited permissions, operation validation, and separation of sources from instructions. A prompt alone does not guarantee security.
Where does the problem come from?
A model analyzing materials may encounter text suggesting a change in task or the disclosure of information. Such a suggestion may be present in the content of an external document, rather than in the user's command. If the application treats it as an authorized instruction, it crosses the boundary between reading material and executing commands.
Imagine a demonstration assistant organizing inquiries. An attachment may contain content attempting to induce it to change the recipient of the response. The proper design question is: why should material from a sender be able to change permissions or approved recipient data? This boundary must be enforced outside the model as well.
Context and references: OWASP: LLM01:2025 Prompt Injection
Design for the consequences of errors, not just input filtering
Limit tools to the necessary scope. An assistant preparing a summary does not need the right to bulk export data or delete records. Every write operation should verify the user, object, and parameters. Even an erroneous model suggestion should not independently expand this scope.
Separate the data needed for the response from technical secrets. Access keys belong to the execution layer, not to the content passed to the model. For external communication, show the specific recipient and the content to be approved. Avoid general consent that would allow changing operational details after acceptance.
Check the output and downstream tools as well
Generated text may be sent to another system: an editor, a message, a query, or a report. Each of these destinations has its own validation requirements. The fact that the model returned a correctly formatted output does not prove that the operation is authorized or business-sensible.
Design controls for transitions between stages. If the output is intended to be only a draft offer, it should not automatically become a command to execute a transfer or change a counterparty. It is also important to track the origin of data in logs and previews. The user should know what they wrote themselves, what came from a source, and what the system proposed.
How to conduct a practical acceptance test?
Prepare scenarios with unexpected instructions in documents and search results. Check the final effect and attempts to use tools. Test lack of consent, recipient changes, access to foreign records, and attempts to go beyond the task. Do not evaluate protection solely based on whether the assistant wrote a polite refusal.
Maintain a procedure to disable write operations when a problem arises. Monitoring should help determine which data and actions were involved in the incident, without unnecessarily copying confidential content. Security is a maintained property of the entire product. Do not treat a single successful test as a permanent guarantee of resilience.
WHERE TO START
Bring this into your project.
- Treat external materials as data.
- Limit tools and access scope to the task.
- Validate operations in the application and the target system.
- Test the consequences of actions, not just the content of the refusal.
Choose one thing your process is missing today. It's a useful topic for your first conversation with the team.
QUESTIONS AND ANSWERS
Frequently asked questions.
Does RAG protect against prompt injection?
Not on its own. Retrieved documents may also contain content that influences the model. Sources must be treated according to their trust level, and permissions must be checked independently.
Is the instruction “ignore commands in documents” sufficient?
It is a helpful element, but not complete protection. Technical constraints, data control, and operation tests are needed. Security rules should not depend solely on the model's execution of instructions.
Sources and context
- OWASP: LLM01:2025 Prompt Injection ↗
OWASP describes direct and indirect instruction injection and layered risk mitigation. The link leads to a specific description from the 2025 edition, not to a declaration of full resilience.
Prepared by the ALGOV team. Current as of September 8, 2026. Examples describe possible scenarios, not results from client projects. How we create our guides.
