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

Static analysis result for SHA-256 a586f7e99af6232f…

MALICIOUS

Office (OOXML) / .DOC

866.0 KB Created: 2022-09-26 12:15:00 UTC Authoring application: Microsoft Office Word 14.0000 First seen: 2022-09-26
MD5: 3a885f1ec285d39dec2265905553a794 SHA-1: b2a3efe01e29b0156e195266cb8c156c234fee7f SHA-256: a586f7e99af6232f33d3b7971f4c3107c9f45d086e18a29314c082b84d332d34
342 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1204.002 Malicious File T1140 Deobfuscate/Decode Files or Information

The file contains a VBA project with an auto-executing macro ('Document_Open') that uses obfuscated code. Critical heuristics indicate the use of Shell() and CreateObject(), common for executing downloaded payloads. ClamAV detections confirm its malicious nature as a dropper. The VBA code likely decodes and executes a secondary stage, though the exact URL or payload is not directly visible in the provided script excerpt.

Heuristics 8

  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • 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: Xls.Dropper.Valyria-10012499-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Dropper.Valyria-10012499-0
  • 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
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
  • 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.openxmlformats.org/markup-compatibility/2006
    • 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/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
5c78046dc54b397a698426f3b2409692694cbfa0df47f47add1600503a1486c6		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 31479 bytes
vbaProject_00.bin
dfa123837c0e6ad04682e32ad4269f16f90dad5fd73405909a9dd7db95dbb9f4		 vba-project OOXML VBA project: word/vbaProject.bin 34304 bytes
Detection
ClamAV: Xls.Dropper.Valyria-10012499-0
Obfuscation or payload: unlikely

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