SquirrelWaffle — Office (OLE) / .XLS malware analysis

Static analysis result for SHA-256 938e2c76b7cb5805…

MALICIOUS

Office (OLE) / .XLS

234.5 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel
MD5: 93228553f3055dc40e935e05c6491889 SHA-1: a96f7ba8c62913b8db220000211789070624106f SHA-256: 938e2c76b7cb5805b297b2c6f8ece0f8e43c854639bec1a3decc78f1cf74bd1f
262 Risk Score

Malware Insights

SquirrelWaffle · confidence 95%

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

The sample contains Excel 4.0 macros, specifically an Auto_Open macro that utilizes dangerous functions like RUN. These macros reconstruct and attempt to access three distinct URLs, indicating a downloader functionality. ClamAV detection further confirms its malicious nature as SquirrelWaffle. The reconstructed URLs are the primary indicators of compromise.

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://stonehill-ng.com/hBGcyAWq/bold.html
    • http://vodvarkasprings.com/2iA9V3YM/bold.html
    • https://nile-plast.com/3JjLWLsWK0/bold.html

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
4cf2a699615a40072cafed6035576a91369937485cd5780ccad3a0d91a3a0e4f		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 11118 bytes

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