SquirrelWaffle — Office (OLE) / .XLS malware analysis

Static analysis result for SHA-256 eb837da9212fc45a…

MALICIOUS

Office (OLE) / .XLS

241.5 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel
MD5: 5069606cb8d0875796b1b14e877fe0e2 SHA-1: 5e4c58bddc3652229ac76cc2bb6446d9562d5dec SHA-256: eb837da9212fc45a0d39be96afa4ff5e342e06cc52295efec17996d414f2420a
262 Risk Score

Malware Insights

SquirrelWaffle · confidence 95%

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

The file is an Excel XLS document containing Excel 4.0 (XLM) macros, specifically an Auto_Open macro. Heuristics indicate the use of dangerous formula APIs like RUN. The macros reconstruct and reference two URLs: "https://araconsultoriaysoluciones.com/TTopI2OxX/goh.gif" and "https://lakisuru.com/Robhp9cnJJ/goh.gif". ClamAV identifies the file as Xls.Downloader.SquirrelWaffle. The primary intent appears to be downloading and executing a second-stage payload from these URLs.

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 (2 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: Xls.Downloader.SquirrelWaffle1021-9903731-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.SquirrelWaffle1021-9903731-0
  • 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://araconsultoriaysoluciones.com/TTopI2OxX/goh.gif
    • https://lakisuru.com/Robhp9cnJJ/goh.gif

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
49c557fd2d54f31f543797409444c8834119eedd1a3c3daad99272cc3e2c1f0f		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 11075 bytes

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