SquirrelWaffle — Office (OLE) / .XLS malware analysis

Static analysis result for SHA-256 3be1cfc979cb0a81…

MALICIOUS

Office (OLE) / .XLS

229.0 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel First seen: 2021-10-01
MD5: 5a8975f1b4b3789a00411f6c006b356e SHA-1: cc68b8eaefff29afa99c42105305456c426120c4 SHA-256: 3be1cfc979cb0a815e32981cd18da494389c9015915a3415c1ecfa21161158e1
302 Risk Score

Malware Insights

SquirrelWaffle · confidence 95%

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

The file contains Excel 4.0 macros with an Auto_Open entry, which is a critical indicator of malicious intent. The macros reconstruct and reference three distinct URLs: 'https://dharmasasthatrust.com/cEJYcStqlAf/hr.html', 'https://shalsa3d.com/UGqWNCLT/hr.html', and 'https://haroldhallroofing.net/pAz8O63Gn/hr.html'. These URLs are likely used to download and execute a secondary payload, consistent with the SquirrelWaffle family's known behavior. The presence of ShellExecute API calls further supports the execution of external code.

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://dharmasasthatrust.com/cEJYcStqlAf/hr.html
    • https://shalsa3d.com/UGqWNCLT/hr.html
    • https://haroldhallroofing.net/pAz8O63Gn/hr.html

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
e515aea77033b51661d68793c809b89632ac2f97755cd11b999a378d8e47fb92		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 8702 bytes

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