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

Static analysis result for SHA-256 f9f11c75d698ff9b…

MALICIOUS

Office (OOXML) / .DOC

249.1 KB Created: 2021-11-23 08:56:00 UTC Authoring application: Microsoft Office Word 16.0000
MD5: d7a1c55ef46132c7a1feb84cafe286cb SHA-1: ca2f302156f8830bd2f941eba043317edf673df1 SHA-256: f9f11c75d698ff9b885c953cfd22a32a7625db03c5e22051e376bb1a6861d56a
270 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic for Applications T1204.002 User Execution: Malicious File T1105 Ingress Tool Transfer T1027 Obfuscated Files or Information T1036

The sample is a malicious Word document containing an AutoOpen macro that drops several files to disk. The script reconstructs several paths: 'C:\Users\<USER>\AppData\Local\Microsoft\Windows\COM Surrogate\dllhost.exe', 'C:\Users\<USER>\AppData\Local\//instx.exe', 'C:\C:\cfe91497d9137b2\ffd0.exe', and 'C:\cfe91497d9137b92\COVID-19.docx'. It uses Base64 decoded data from a 'manager' object to write these files to the system, using 'cmd /c REG A' to execute them or modify registry keys for persistence. The use of 'Environ' to resolve localappdata and temp directories is typical of dropper behavior.

Heuristics 8

  • ClamAV: Ole2.Macro.Agent-9858864-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Ole2.Macro.Agent-9858864-1
  • 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.
  • AutoOpen macro high OLE_VBA_AUTOOPEN
    AutoOpen macro
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
  • Suspicious extracted artifact high EXTRACTED_FILE_STATIC_TRIAGE
    One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.
  • VBA project inside OOXML medium OOXML_VBA
    Document contains vbaProject.bin — 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/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
76eaf2738a46ee2b21b6f2204f83cba35d2b27269e93be70eb643ec517aa2f67		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 6534 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved macro source contains an auto-exec entry point and execution/download terms.
vbaProject_00.bin
b6a508a06a82383a31223dfb357554263312dfa285af6f197a8d87cf19228a6c		 vba-project OOXML VBA project: word/vbaProject.bin 325632 bytes
Detection
ClamAV: Ole2.Macro.Agent-9858864-1
Obfuscation or payload: likely
Carved artifact contains 7 long base64-like blob(s). Carved macro source contains an auto-exec entry point and execution/download terms.

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