Malicious Office (OOXML) / .DOC — malware analysis report

Static analysis result for SHA-256 66f8d5a9e9c00762…

MALICIOUS

Office (OOXML) / .DOC

184.0 KB Created: 2020-12-12 17:13:00 UTC Authoring application: Microsoft Office Word 16.0000
MD5: 83a23ce6242af5152a32f79dddc5b7a4 SHA-1: 6cfc5ed55278c9ef9b6b9576056f1025c26d8c76 SHA-256: 66f8d5a9e9c007625c203ee4e3e5f54669e160ee47438b2d895abb081b7eb82d
382 Risk Score

Malware Insights

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

The sample contains a VBA macro with a Document_Open subroutine that executes a secondary macro, Htyf. This macro utilizes WScript.Shell and CreateObject to download a file from an embedded URL and save it as 'C:\users\public\3dft.so'. It then attempts to execute this downloaded file using a command that appears to involve PowerShell. The presence of multiple critical heuristics related to VBA, Shell execution, and HTTP downloads strongly indicates a downloader functionality.

Heuristics 9

  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • WScript.Shell usage critical OLE_VBA_WSCRIPT
    WScript.Shell usage
  • 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.
  • ClamAV: Doc.Downloader.87f88707f007f878-OOXML-9981544-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.87f88707f007f878-OOXML-9981544-0
  • Document_Open macro high OLE_VBA_DOCOPEN
    Document_Open macro
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
  • 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.
  • VBA project inside OOXML medium OOXML_VBA
    Document contains a VBA project — VBA macros present
  • 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
    • http://schemas.microsoft.com/office/drawing/2014/chartex
    • http://schemas.microsoft.com/office/drawing/2015/9/8/chartex
    • http://schemas.microsoft.com/office/drawing/2015/10/21/chartex
    • http://schemas.microsoft.com/office/drawing/2016/5/9/chartex
    • http://schemas.microsoft.com/office/drawing/2016/5/10/chartex
    • http://schemas.microsoft.com/office/drawing/2016/5/11/chartex
    • http://schemas.microsoft.com/office/drawing/2016/5/12/chartex
    • http://schemas.microsoft.com/office/drawing/2016/5/13/chartex
    • http://schemas.microsoft.com/office/drawing/2016/5/14/chartex
    • http://schemas.openxmlformats.org/markup-compatibility/2006
    • http://schemas.microsoft.com/office/drawing/2016/ink
    • http://schemas.microsoft.com/office/drawing/2017/model3d
    • http://schemas.openxmlformats.org/officeDocument/2006/relationships
    • http://schemas.openxmlformats.org/officeDocument/2006/math
    • http://schemas.microsoft.com/office/word/2010/wordprocessingDrawing
    • http://schemas.openxmlformats.org/drawingml/2006/wordprocessingDrawing
    • http://schemas.openxmlformats.org/wordprocessingml/2006/main
    • http://schemas.microsoft.com/office/word/2010/wordml
    • http://schemas.microsoft.com/office/word/2012/wordml
    • http://schemas.microsoft.com/office/word/2016/wordml/cid
    • http://schemas.microsoft.com/office/word/2015/wordml/symex
    • http://schemas.microsoft.com/office/word/2010/wordprocessingGroup
    • http://schemas.microsoft.com/office/word/2010/wordprocessingInk
    • http://schemas.microsoft.com/office/word/2006/wordml
    • http://schemas.microsoft.com/office/word/2010/wordprocessingShape

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
6c5de9fc88f17e4358551575897cb4ea3ae6d5aebf2cbf8fa0e2ce7c4b6259e8		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 2238 bytes
vbaProject_00.bin
cd8d39672b6d557603f6445f892c58cb531f0a22d77d2ebe49e249712867b622		 vba-project OOXML VBA project: word/vbaProject.bin 98304 bytes

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