SquirrelWaffle — Office (OLE) / .XLS malware analysis

Static analysis result for SHA-256 c0a3994bb5140514…

MALICIOUS

Office (OLE) / .XLS

233.5 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel
MD5: 76c5b3c16a42fd876d3c8648063ebefd SHA-1: 17eb233138408ec24ee1d300c7fdec089d534766 SHA-256: c0a3994bb5140514f73ecfb49ba1f8a74c2cf3c31dde10c79fa5b8f615ce16b4
302 Risk Score

Malware Insights

SquirrelWaffle · confidence 95%

MITRE ATT&CK
T1059.005 Service Execution: Visual Basic T1204.002 Malicious File Execution: User Execution of Malicious File T1059.001 Command and Scripting Interpreter: PowerShell T1059.003 Command and Scripting Interpreter: Windows Command Shell

The file contains Excel 4.0 macros, specifically an Auto_Open macro, which is a critical finding. The macros reconstruct and reference three URLs, indicating a downloader functionality. The ClamAV detection as 'Xls.Downloader.SquirrelWaffle1021-9903731-0' strongly suggests the SquirrelWaffle family. The ShellExecute API reference further supports the execution of external content.

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://safalerp.com/J1wlINw7HtJ/siera.xml
    • https://godschildrenaf.org/qxwbRMzrqoWK/siera.xml
    • https://callgirlsandescortkenya.site/hllzvTuU/siera.xml

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
3ffa2b64709ec73196f80c6dc868f3f5475b8dfc14c741aa88128f33fdbdad34		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 8699 bytes

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