Detect mailcap.findmatch pickle payloads#69
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massy-o
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May 14, 2026
| "imaplib": {"IMAP4_stream"}, # IMAP4_stream executes commands via subprocess.Popen(command, shell=True) | ||
| "lib2to3.pgen2.grammar": {"Grammar.loads"}, | ||
| "lib2to3.pgen2.pgen": {"ParserGenerator.make_label"}, | ||
| "mailcap": {"findmatch"}, # mailcap.findmatch executes matching entry test commands via os.system() |
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Self-review: this promotes mailcap.findmatch from suspicious to dangerous because the callable can execute a mailcap test command via os.system() during unpickling.
massy-o
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May 14, 2026
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| def test_scan_pickle_bytes_flags_mailcap_findmatch(): |
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Self-review: the regression payload mirrors the bypass shape without executing a real shell command in the test; the scanner only needs to see the mailcap.findmatch global.
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Summary
mailcap.findmatchas a dangerous pickle globalmailcap.findmatchWhy
mailcap.findmatchcan execute a matching mailcap entrytestcommand viaos.system(). Treating it as suspicious only leaves CLI scans with zero dangerous globals and exit code 0.Testing
uv run --with-editable . --with pytest --with numpy --with py7zr pytest tests/test_scanner.py::test_scan_pickle_bytes_flags_mailcap_findmatch tests/test_scanner.py::test_scan_pickle_bytes