SquirrelWaffle — Office (OLE) / .XLS malware analysis

Static analysis result for SHA-256 2f6a1115a13cc48c…

MALICIOUS

Office (OLE) / .XLS

251.5 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel First seen: 2021-10-23
MD5: 52ae8e3c4fce340e36cc877e5e6f0136 SHA-1: 4dabbf6abeb56e56dead83a13bfc5a6e6079e79f SHA-256: 2f6a1115a13cc48c25a660788cf505e17b06d684d929f9b10c89b9548282993c
262 Risk Score

Malware Insights

SquirrelWaffle · confidence 95%

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

The file contains Excel 4.0 macros, specifically an Auto_Open routine that utilizes dangerous functions like RUN. The macros reconstruct and embed three URLs which are likely used to download and execute a second-stage payload. ClamAV detection further confirms this as SquirrelWaffle, a known downloader.

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://hamzatradersbkr.com/29inpCqpjYK/lipass.html
    • https://judge2win.com/g2Ajdl9OK/lipas.html
    • https://renerodrigues.com.br/vOgdDJDBqdJy/lip.html

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
940aff767f87df05b0eeab3cec8b6bdbe9ff72f0669db4f4d953c86c562fe0cd		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 11074 bytes

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