SquirrelWaffle — Office (OLE) / .XLS malware analysis

Static analysis result for SHA-256 f4f2e8efe9c1513a…

MALICIOUS

Office (OLE) / .XLS

235.0 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel
MD5: 67bc0b9a18bec086acbe6d0e94a8c285 SHA-1: 0a77679417f800dd242316e0e7177cc6560943a5 SHA-256: f4f2e8efe9c1513a738a74226454d282c63ae68f944ba2b7f5ef53e15becf70c
262 Risk Score

Malware Insights

SquirrelWaffle · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic for Applications T1204.002 Malicious File T1059.001 PowerShell

The file contains Excel 4.0 macros, specifically an Auto_Open macro that utilizes dangerous functions like RUN. The macros reconstruct and reference three URLs, indicating a downloader functionality. ClamAV identifies the file as Xls.Downloader.SquirrelWaffle, supporting the downloader attack pattern. The reconstructed URLs are the primary IOCs for this stage of the attack.

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://laresumeservice.com/cymxrDQLGo9i/estimate.html
    • https://medicahealthy.net/HZHWZYIq/estimat.html
    • http://pinakidigital.com/vNlUFyxQUW/estima.html

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
5e8ff13675c4fd39e2f06a809a3bf386a38dc86cf57484bef0b10a5599c21569		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 10967 bytes

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