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

Static analysis result for SHA-256 b61eefecc579a330…

MALICIOUS

Office (OLE) / .XLSX

134.5 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel
MD5: 0a435c0bb149562b1e5064d9c4f9a9cf SHA-1: 1d71fc57e0444e0fa6552ae37b38c6b527363812 SHA-256: b61eefecc579a3300b10822e480f51d0cea9558dfb047a6774473185b15877c3
262 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Service Execution: Visual Basic T1204.002 Malicious Link: User Execution

The file contains Excel 4.0 macros, specifically an Auto_Open entry, which is a critical indicator of malicious intent. These macros are designed to execute dangerous formula APIs, including 'RUN', and reconstruct URLs from cell arrays. The primary function of these macros is to download and execute a second-stage payload from one of the five embedded URLs. The ClamAV detection further supports the malicious classification.

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 (5 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.EmotetRed02222-9938635-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.EmotetRed02222-9938635-0
  • 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 http://docs-construction.com/wp-admin/a0mJP2Adw5YTHt/
    • http://laohange.com/wp-content/0qJRIjTThZ/
    • http://centrobilinguelospinos.com/wp-admin/EIzEADnvS/
    • http://stancewheels.com/wp-admin/b5xkQkgEFiBmW/
    • http://jeffreylubin.igclout.com/wp-admin/0WGa0yF6b6F3VK5tb/

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
be1ac9f30af65ef180310243cbba4a51ea41ae015d1d5e2b649c82e30f6f4b5c		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6365 bytes

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