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

Static analysis result for SHA-256 6a0e3abf6bc6647d…

MALICIOUS

Office (OLE) / .XLS

321.5 KB Created: 2021-02-04 12:47:35 Authoring application: Microsoft Excel
MD5: 383cef23d1f544368bfccdc96acc8cac SHA-1: 396dfdf150bf895031922f4463155afc8d711467 SHA-256: 6a0e3abf6bc6647dc103495d7cdcf4ea64840d36eff6f3a0d74868cb4da50723
262 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File

The file is an Excel spreadsheet containing Excel 4.0 macros, specifically an Auto_Open macro that is designed to execute automatically. This macro is configured to download a payload from the URL https://distribuidoramc.com/ds/0502.gif. The presence of dangerous formula APIs and the ClamAV detection further support its malicious nature as a downloader.

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 (1 URL) 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.Docusign0521-9864805-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.Docusign0521-9864805-0
  • 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://distribuidoramc.com/ds/0502.gif
    • https://distribuidoramc.com/ds/0502.gif�

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
686b5a84e5fca1802ca1eb58bb931c0c5c87c16b6298dca8b4ea493ed1e5607a		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 4317 bytes

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