feat(backend): Add ClamAV scanning for local file paths

[Otto-AGPT]

Context

From PR #11796 review discussion. Files processed by the video blocks (downloads, uploads, generated videos) should be scanned through ClamAV for malware detection.

Problem

store_media_file() in backend/util/file.py already scans:

• workspace:// references
• Cloud storage paths
• Data URIs (data:...)
• HTTP/HTTPS URLs

But local file paths were NOT scanned. The else branch only verified the file exists.

This gap affected video processing blocks (e.g., LoopVideoBlock, AddAudioToVideoBlock) that:

1. Download/receive input media
2. Process it locally (loop, add audio, etc.)
3. Write output to temp directory
4. Call store_media_file(output_filename, ...) with a local path → skipped virus scanning

Solution

Added virus scanning to the local file path branch:

# Virus scan the local file before any further processing
local_content = target_path.read_bytes()
if len(local_content) > MAX_FILE_SIZE_BYTES:
    raise ValueError(...)
await scan_content_safe(local_content, filename=sanitized_file)

Changes

• backend/util/file.py - Added ~7 lines to scan local files (consistent with other input types)
• backend/util/file_test.py - Added 2 test cases for local file scanning

Risk Assessment

• Low risk: Single point of change, follows existing pattern
• Backwards compatible: No API changes
• Fail-safe: If scanning fails, file is rejected (existing behavior)

Closes SECRT-1904

[coderabbitai]

Walkthrough

Reads local file bytes in store_media_file, enforces MAX_FILE_SIZE_BYTES, and performs an asynchronous virus scan (scan_content_safe) with the sanitized filename before continuing; tests added to validate scanning and virus-detection propagation for local paths.

Changes

Cohort / File(s)	Summary
Local File Security Scanning autogpt_platform/backend/backend/util/file.py	Reads local file content, enforces MAX_FILE_SIZE_BYTES, and calls async scan_content_safe with file bytes and sanitized filename for local (non-cloud) paths before further processing.
Local File Test Coverage autogpt_platform/backend/backend/util/file_test.py	Adds two async tests: test_store_media_file_local_path_scanned (mocks local path resolution and virus scan invocation) and test_store_media_file_local_path_virus_detected (ensures VirusDetectedError propagates).

Sequence Diagram(s)

sequenceDiagram
  participant Client
  participant Store as store_media_file
  participant FS as LocalFS
  participant Scanner as ClamAVScanner

  Client->>Store: submit local file path
  Store->>FS: resolve & open file (read bytes)
  FS-->>Store: file bytes
  Store->>Scanner: scan_content_safe(bytes, sanitized_filename)
  alt scan ok
    Scanner-->>Store: scan result OK
    Store->>Client: continue processing / return local filename
  else virus detected
    Scanner-->>Store: raises VirusDetectedError
    Store-->>Client: propagate error
  end

Loading

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~12 minutes

Possibly related PRs

• fix: add virus scanning to WorkspaceManager.write_file() #11990 — Adds explicit scan_content_safe call in a file-persistence path (WorkspaceManager.write_file), related to adding ClamAV scanning to local file flows.

Suggested labels

size/s

Suggested reviewers

• Pwuts

Poem

🐰 I nibble bytes with careful pace,

I scan each file in every place,
ClamAV keeps my burrow neat,
No sneaky viruses to meet,
Hooray — secure files for the race! 🎩

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately describes the main change: adding ClamAV scanning for local file paths in the backend.
Description check	✅ Passed	The description provides relevant context about the security gap and the solution implemented for scanning local file paths in the store_media_file function.
Linked Issues check	✅ Passed	The PR implements the core requirement from SECRT-1904 by adding ClamAV scanning to local file paths in the store_media_file function, following the same pattern used for other input types.
Out of Scope Changes check	✅ Passed	All changes are directly related to the stated objective of adding virus scanning for local file paths; no out-of-scope modifications are evident.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

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✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch otto/secrt-1904-clamav-local-files

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📒 Files selected for processing (1)

• autogpt_platform/backend/backend/util/file.py

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• autogpt_platform/backend/backend/util/file.py

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[ntindle]

✅ Reviewed: Closes security gap where local file paths weren't virus-scanned.

• Reads file bytes, checks size, calls existing scan_content_safe()
• Good test coverage (scan called + virus detected scenarios)
• Simple, focused fix

LGTM

[qodo-code-review]

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