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

Static analysis result for SHA-256 0a3c66a25ee6eb50…

MALICIOUS

Office (OOXML) / .DOC

3.24 MB Created: 2022-07-17 16:42:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2022-08-01
MD5: 24a2c8b07defea8c02cd94d2261ad39f SHA-1: 80bb2212fcf06f014b32e05f3e3292c1c7a0f30f SHA-256: 0a3c66a25ee6eb50991ed7e3ffc3637f74048eddb1ae50cba93b073babec94b1
402 Risk Score

Malware Insights

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

This OOXML document contains a VBA macro that acts as a shellcode loader. The macro is obfuscated and uses functions like VirtualProtect to execute code in memory. The presence of a Document_Open macro and the ClamAV detection signature 'Doc.Downloader.8a5a5aca5aca5a7a-OOXML-9981537-0' strongly indicate that this file is designed to download and execute a secondary malicious payload.

Heuristics 10

  • VBA property-stored shellcode loader critical OLE_VBA_PROPERTY_SHELLCODE_LOADER
    VBA auto-exec macro takes the address (VarPtr) of a byte buffer decoded from a document property, marks memory executable (VirtualProtect/VirtualAlloc), and transfers control through a callback API (e.g. SetTimer/EnumWindows). The payload is hidden in the document properties rather than the macro source — the SVCReady loader pattern, a native shellcode runner rather than a parser CVE.
  • Obfuscated auto-exec VBA loader critical OLE_VBA_OBFUSCATED_AUTOEXEC_LOADER
    Auto-exec VBA reconstructs strings with a heavy custom decoder (numeric char-array, repeated hex-string decode, or junk-token Replace removal) and feeds them to a COM-instantiation or execution sink. This obfuscated-loader shape keeps CreateObject/Shell/URL indicators out of the macro source.
  • ClamAV: Doc.Downloader.8a5a5aca5aca5a7a-OOXML-9981537-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.8a5a5aca5aca5a7a-OOXML-9981537-0
  • OOXML part with non-standard content type and high-entropy data high OOXML_BOGUS_CUSTOM_PART
    The package declares a part with an invented content type (not an OpenXML/Office/standard media type) holding large, high-entropy (likely encrypted/packed) data. Legitimate OOXML files do not carry opaque binary blobs under custom content types; this is the embedded next-stage payload pattern used by loaders such as SVCReady.
  • VBA project part renamed to evade filename detection high OOXML_VBA_PROJECT_RENAMED
    The VBA project is bound through the OOXML relationship/content type but its part is not named vbaProject.bin. Legitimate Office producers always emit vbaProject.bin; renaming it hides the macros from path-only scanners (observed in the SVCReady loader).
  • Document_Open macro high OLE_VBA_DOCOPEN
    Document_Open macro
  • GetObject call high OLE_VBA_GETOBJ
    GetObject call
  • VBA reads reversed config from document properties high OLE_VBA_REVERSED_DOCPROP_CONFIG
    VBA applies StrReverse to values read from the document's custom/built-in properties. Storing reversed configuration (URLs, CLSIDs, env-var names, payload names) in document properties keeps indicators out of the macro source — an obfuscation technique used by the SVCReady loader.
  • VBA project inside OOXML medium OOXML_VBA
    Document contains a VBA project — VBA macros present (project part renamed away from vbaProject.bin: word/CTbINgUyyn.bin)
  • 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.microsoft.com/office/2019/extlst
    • 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/2020/wordml/sdtdatahash
    • 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
88461e99f56f4642816726d83681ed958b2ccd121029153c47f7962673037d48
vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 6268 bytes
vbaProject_00.bin
26ac623f56e287eb2ee7f8b4001abd2869614c6fc7f249f0b07351465612ac1f
vba-project OOXML VBA project: word/CTbINgUyyn.bin 13312 bytes