Malicious Office (OLE) / .XLS — malware analysis report

Heuristics 6

• Excel 4.0 Auto_Open defined name critical OLE_XLM_AUTOOPEN_DEFINEDNAME
  oletools recovered an Auto_Open / Auto_Close entry from an Excel 4.0 macro sheet. The raw BIFF name can be tokenized or partially opaque to byte-string checks, but the recovered macro listing confirms the workbook has an XLM auto-execution entry.
• XLM Auto_Open with dangerous formula APIs critical OLE_XLM_DANGEROUS_FN
  Excel 4.0 macro sheet contains an Auto_Open / Auto_Close entry and dangerous XLM formula APIs that can invoke programs, write files, or transfer control without VBA.
• URL reconstructed from XLM cell array (3 URLs) critical OLE_XLM_CELL_ARRAY_URL
  Excel 4.0 macro sheet stages its payload URL across the BIFF8 Shared String Table (one quoted-char SST entry concatenated with & at runtime) or across individual numeric cells (one ASCII charcode per cell). The reconstructed URL is invisible to literal-bytes URL extraction because it is never contiguous in the workbook stream. URLs were recovered by walking the BIFF8 record stream and decoding SST entries plus LABELSST/RK/NUMBER cells.
• ClamAV: Doc.Downloader.Qbot12212-9916031-0 critical CLAMAV_DETECTION
  ClamAV detected this file as malware: Doc.Downloader.Qbot12212-9916031-0
• Excel 4.0 (XLM) macro sheet present medium OLE_XLM_AUTOOPEN
  Workbook contains an Excel 4.0 macro sheet sub-stream — XLM is rarely seen in modern legitimate workbooks and was a major Office malware vector during 2020-2022.
• Embedded URL info EMBEDDED_URL
  One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
  URL https://greenflag.esp.br/yuINdRbM/tiynh.html

  • https://noithat117.vn/TSh7GBeIR/tiynh.html
  • https://playsis.com.br/qJSL1BN5V/tiynh.html

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