SquirrelWaffle — Office (OLE) / .XLS malware analysis

Static analysis result for SHA-256 bc5c49d5b235d634…

MALICIOUS

Office (OLE) / .XLS

243.0 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel
MD5: 956bba3f1222ebd59254153c1da5b2c8 SHA-1: d576c9090a491e51b3aef24bfa10cde3e2c3973c SHA-256: bc5c49d5b235d6344dde063f90edb4f5246ebf1cfc809415d4c9899a952ec711
262 Risk Score

Malware Insights

SquirrelWaffle · confidence 95%

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

The sample is an Excel 4.0 macro-enabled spreadsheet that leverages the Auto_Open function to execute. Critical heuristics indicate the presence of dangerous formula APIs and reconstructed URLs from cell arrays. The script concatenates strings to form the URLs: "h"&"tt"&"ps://meet"&"trust.in/aMZID8gQ/u.h"&"t"&"m"&"l", "h"&"tt"&"ps://aqi"&"ssa"&"rafood.com.my/eAu"&"610r"&"n3w8V/u.h"&"t"&"m"&"l", and "h"&"tt"&"ps://ra"&"dio"&"ca"&"ca.top/RVDXQ4D7cWU6/u.h"&"t"&"m"&"l". These URLs are likely used to download and execute a second-stage payload. ClamAV detection further confirms its malicious nature as SquirrelWaffle.

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://meettrust.in/aMZID8gQ/u.html
    • https://aqissarafood.com.my/eAu610rn3w8V/u.html
    • https://radiocaca.top/RVDXQ4D7cWU6/u.html

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
b2a877bdb8389e2570b173ae2439bcb709e9c36c1a58ccad6500a6edc8a2ee2e		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 11543 bytes

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