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

Static analysis result for SHA-256 631f2fe3e908d0ac…

MALICIOUS

Office (OLE) / .XLSX

145.5 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel
MD5: aa09a813f957433c6d4b4bf678971f56 SHA-1: 3cd5b7406c8a13d1dcbb89a24675799ba93f8bda SHA-256: 631f2fe3e908d0ace885a1bdccb3a5d2fb32ef0b4043917e2bbb24e470020faa
262 Risk Score

Malware Insights

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

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 API functions, including registering a server and downloading payloads from multiple URLs. The reconstructed URLs indicate a downloader functionality, likely to fetch and execute a second-stage payload.

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://teamsandeep.com/wp-content/p3f2n6wc4nwfg/
    • https://csinoticias.com/wp-includes/RnHjIzg/
    • http://landorestates.com/wordpress/NELf96wr/
    • https://www.rockwoodsaloon.com/wp-admin/A706GTXNufQSWXG52/
    • http://butziger.com/meettiming/hBJCeNGAvBpGZoD7ee/

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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