Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 a10cbbcd50fffa2e…

MALICIOUS

Office (OOXML)

18.3 KB Created: 2021-07-26 04:10:00 UTC Authoring application: Microsoft Office Word 16.0000
MD5: d5df78867dded0a2a9d3fdd3d16381c2 SHA-1: 450ff338b55ce829ba6eacbf2e321dacc3c570f7 SHA-256: a10cbbcd50fffa2eb44308921d916ed54381600e19ae5f222e263091dec17780
290 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 a Document_Open auto-execution routine. This macro utilizes the URLDownloadToFileA API to download a file from 'https://the.earth.li/~sgtatham/putty/latest/w64/putty.exe' and saves it as '%TEMP%\putty.EXE'. Subsequently, it uses ShellExecuteA to execute the downloaded file. This behavior is indicative of a downloader or droppper malware.

Heuristics 8

  • URLDownloadToFile in VBA critical OLE_VBA_DOWNLOAD
    URLDownloadToFile in VBA
  • ClamAV: Doc.Downloader.Bartalex-6755229-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.Bartalex-6755229-0
  • ClamAV detection on extracted artifact critical EXTRACTED_FILE_CLAMAV
    ClamAV flagged at least one file extracted from inside this sample. Even when the wrapping document carries no AV detection of its own, a hit on the carved artifact is a strong indicator the sample is a delivery vehicle.
  • Document_Open macro high OLE_VBA_DOCOPEN
    Document_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.
  • VBA project inside OOXML medium OOXML_VBA
    Document contains a VBA project — VBA macros present
  • 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
    • 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/2018/wordml/cex
    • http://schemas.microsoft.com/office/word/2016/wordml/cid
    • http://schemas.microsoft.com/office/word/2018/wordml
    • 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
    • https://the.earth.li/~sgtatham/putty/latest/w64/putty.exe

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
557eaa1be459355bfb39ece8f6c2816045e3ede9ecc9b0c0cb92bab9be7f7c4f		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 1483 bytes
vbaProject_00.bin
28139f9896aa90bdb55be5c7d8da328b068a81dab3ce576fd829fed3149b7144		 vba-project OOXML VBA project: word/vbaProject.bin 10752 bytes
Detection
ClamAV: Doc.Downloader.Bartalex-6755229-0
Obfuscation or payload: unlikely
emf_00.emf
bb7f7a12f3fdf0bd84deb5b4d99d3531270d8d630ec4b0d75c7020125ad573aa		 ooxml-emf OOXML EMF part: docProps/thumbnail.emf 3528 bytes

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