SquirrelWaffle — Office (OLE) / .XLS malware analysis

Static analysis result for SHA-256 3f3f21189390158a…

MALICIOUS

Office (OLE) / .XLS

244.5 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel
MD5: fa6369788a5f5490d4c506e65b82a166 SHA-1: f12d615a708cd6e83c669e3a16c1bebbf2510718 SHA-256: 3f3f21189390158abe6d01848ce995c762f3b0e908ea27192778effb160a6014
302 Risk Score

Malware Insights

SquirrelWaffle · confidence 95%

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

The file contains Excel 4.0 macros that are configured to execute automatically via the Auto_Open function. These macros reconstruct and access three distinct URLs, which are likely used to download and execute a second-stage payload. The ClamAV detection and heuristic firings strongly indicate this is a downloader, specifically identified as SquirrelWaffle.

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://gillcart.com/Cdpmoyhr/key.xml
    • https://geit.in/MeOlE9Xxd/key.xml
    • https://mercanets.com/9DPZqAfZdq5z/key.xml

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
0cc5d90f832ce63697b5e33755a85678cc92f39cb992f627f4dc600fc210b3fa		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 8653 bytes

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