SquirrelWaffle — Office (OLE) / .XLS malware analysis

Static analysis result for SHA-256 15f8092442829455…

MALICIOUS

Office (OLE) / .XLS

229.0 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel
MD5: f9483ef292a093afcf414b7bc7ebb098 SHA-1: 7cd3928a37c1edc48f1ebcb5d2d8e6c850d47329 SHA-256: 15f80924428294550137efe87828bdf5d40c847ed91cabb3d90ff0e414351f15
302 Risk Score

Malware Insights

SquirrelWaffle · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File T1566.001 Spearphishing Attachment

The file is an Excel spreadsheet containing Excel 4.0 macros, specifically an Auto_Open function that utilizes dangerous formula APIs. The macros reconstruct and attempt to download payloads from three distinct URLs. ClamAV detection further confirms its malicious nature as SquirrelWaffle, a known downloader.

Heuristics 7

  • 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
  • Reference to ShellExecute API high SC_STR_SHELLEXEC
    Reference to ShellExecute API
  • 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://dharmasasthatrust.com/cEJYcStqlAf/hr.html
    • https://shalsa3d.com/UGqWNCLT/hr.html
    • https://haroldhallroofing.net/pAz8O63Gn/hr.html

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
e515aea77033b51661d68793c809b89632ac2f97755cd11b999a378d8e47fb92		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 8702 bytes

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