Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 991d4f92e3ceb5c3…

MALICIOUS

Office (OOXML)

29.5 KB Created: 2021-07-11 07:32:00 UTC Authoring application: Microsoft Office Word 15.0000
MD5: 3a0d0f6141bedffca45843ef81c73d10 SHA-1: 7b8a2bcd2c987b92719c89ed45964a12ccb69531 SHA-256: 991d4f92e3ceb5c34154cde4f417ab17ff43719769a5485570f9090d0600bcdd
302 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File T1566.001 Spearphishing Attachment

The sample is a malicious OOXML document containing a VBA macro that is automatically executed via the Document_Open subroutine. The macro attempts to download and execute a second-stage payload from the URL 'http://btlsia.btiat.com/kit.html'. This is supported by high-severity heuristics for VBA macros and CreateObject calls, and a critical ClamAV detection.

Heuristics 8

  • ClamAV: Doc.Downloader.Valyria-10029951-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.Valyria-10029951-0
  • 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.
  • 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
  • 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 (project part renamed away from vbaProject.bin: word/style.rel)
  • 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/2012/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
10fdbccd5c561bb0668f44fa737cda5465c0608cc0ab842621559066ec35326c		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 9276 bytes
vbaProject_00.bin
d1914ee7cc0982ff4145d38b8f0035699450f1d4fc866767c8fd990334514892		 vba-project OOXML VBA project: word/style.rel 45568 bytes
Detection
ClamAV: Doc.Downloader.Valyria-10029951-0
Obfuscation or payload: unlikely

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