SquirrelWaffle — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 67beb6d8f498fc4d…

MALICIOUS

Office (OLE) / .XLSX

247.5 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel
MD5: 4510526f1bce9aca03b9d6cc37817da6 SHA-1: 180cadfc28d01d044bf1666a3b657a032f3c49a6 SHA-256: 67beb6d8f498fc4dd9ed1c8c2313af9b3ec72d23a1abf683308b15fd49791e0f
262 Risk Score

Malware Insights

SquirrelWaffle · confidence 95%

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 defined name, which is a strong indicator of malicious intent. These macros are designed to execute dangerous functions and reconstruct URLs from cell arrays. The reconstructed URLs point to external resources, likely for downloading and executing a second-stage payload, consistent with the SquirrelWaffle family. The ClamAV detection further supports this assessment.

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 (3 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://samtnpy.org/bveCGKTX/ghb.html
    • https://massngo.org/dXKvyKV9v8c/ghb.html
    • https://vathiriyar.org/uy0Tk0keJUr/ghb.html

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
8038cb32870f91f07ba8d77d2b38d0de4989e88a9f0271274f420bb3e000a522		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 11469 bytes

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