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

Static analysis result for SHA-256 15a5f874f7d892d7…

MALICIOUS

Office (OLE) / .XLSX

145.0 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel
MD5: fa933dab83a7b7bb7284d6d880bb1e32 SHA-1: 3537cfabf3d604beb94277a26dd0ea20a8f3f71d SHA-256: 15a5f874f7d892d7d8496bcd4efd4f44821ddc56a059511f2ea8fe28f1a2c2d8
262 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The file contains Excel 4.0 macros, specifically an Auto_Open macro, which is a known technique for executing malicious code. The macros reconstruct and attempt to download payloads from multiple URLs, including "h"&"ttps://terrassa-cafe.com/9yjxnes/18p2S7bBrdpM6FrAc/". This indicates a downloader functionality, likely part of a larger attack chain. The ClamAV detection further supports its malicious nature.

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 https://terrassa-cafe.com/9yjxnes/18p2S7bBrdpM6FrAc/
    • https://moseletronicos.com/wp-content/5/
    • https://sabaithaimassage.com.au/wp-admin/Hgbn3e/
    • https://wiremax.avaspadan.com/admin/ItopibIZF3dxpy0/
    • https://troopsites.com/wp-admin/CzMJm2vfbA4osSHH/

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
71a011c6654bf0f86fe42dabbb7815a8e04c6ae15b5b70864945acbb6f82ced0		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6768 bytes

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