ZIP/OOXML container with non-ZIP prefix bytes

POLYGLOT_ZIP_PREFIXED

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high POLYGLOT_ZIP_PREFIXED

What it means

Non-empty bytes precede the first ZIP local-file header.

Why it fires

Many ZIP-based parsers (including OOXML readers) scan forward to find the central directory and successfully open archives that have arbitrary prefix bytes. Format-aware parsers see only the prefix. Mismatched parser behaviour on the same bytes is a polyglot delivery pattern.

Other General heuristics

POLYGLOT_PDF_APPENDED_ZIP_CVE_BUNDLE EXTRACTED_FILE_CLAMAV POLYGLOT_GIF_PDF_FORCEDENTRY_SHAPE SPEC_DIVERGENCE_HIGH PDF_EXTENSION_MISMATCH POLYGLOT_PDF_ZIP_APPENDED EXTRACTED_FILE_STATIC_TRIAGE CORPUS_HISTORICALLY_MALICIOUS POLYGLOT_TEXT_PDF FORMAT_NEUTRAL_SCAN PPT_FOPT_COMPLEX_DATA_OVERFLOW PPT_FOPT_PROPERTY_TABLE_TRUNCATED CORPUS_RARE_COMBINATION CORPUS_RARE_STRUCTURAL_FEATURE_SET ANALYSIS_TIMEOUT_PARTIAL EMBEDDED_URL MACRO_VALID_PUBLISHER_SIGNATURE SCAN_OPTIONAL_STAGES_SKIPPED POLYGLOT_PDF_APPENDED_ZIP_SCAN_INCOMPLETE SCAN_INCOMPLETE UNKNOWN_FORMAT