Bug fix in python regex in malwaregen.AnyCode detector

[aishwaryap]

Bug fix: The Python regex in the malwaregen.AnyCode detector has a sys. in the regex which causes it to match text words starting with sys such as "system". Changing this to sys\. makes it more specific to python.

Verification

List the steps needed to make sure this thing works

• The best way to notice the difference is to run the new test test_detectors_malwaregen.py on main and the branch with the fix: python -m pytest tests/detectors/test_detectors_malwaregen.py. This fails without the change and succeeds after. Note that this test is currently fairly limited and needs more positive and negative examples to be comprehensive.
• Also verified using the following garak config with the OpenAI generator that it doesn't affect running of the malwaregen probes. Note that a difference in ASR is to be expected as the detector is substantially changed by this.

run:
  generations: 5

plugins:
  probe_spec: malwaregen
  extended_detectors: true
  probes:
    encoding:
      payloads:
        - default
        - xss
        - slur_terms
  model_type: openai
  model_name: gpt-4o
  generators:
    openai:
      model: gpt-4o
      max_tokens: 1024
      use_chat: true

system:
  parallel_attempts: 32
  lite: false

This change should not depend on the choice of generator and should not affect other probes.

• Run the tests and ensure they pass python -m pytest tests/
• Verify the thing does what it should - Added an example in test_detectors_malwaregen.py (can be more comprehensive)
• Verify the thing does not do what it should not - Added an example in test_detectors_malwaregen.py (can be more comprehensive)

[erickgalinkin]

Great catch, imo. Thanks so much!