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

Static analysis result for SHA-256 a7fdf5fe6f3b1c5a…

MALICIOUS

Office (OOXML) / .DOC

117.4 KB Created: 2020-06-24 09:06:00 UTC Authoring application: Microsoft Office Word 16.0000
MD5: 731efe671e53d9df37604f70c022e711 SHA-1: 05e8773781613a259450163ed7c848b2746ec25f SHA-256: a7fdf5fe6f3b1c5a3ac529ca19b479e78465f957b06e5de0e0b41c351f1966c8
340 Risk Score

Malware Insights

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

The sample contains a VBA macro with an AutoOpen function, which is a common technique for initial execution. The macro utilizes URLDownloadToFile in conjunction with StrReverse and WScript.Shell.Exec to download and execute a second-stage payload from a remote source. This indicates a downloader or droppper functionality. The ClamAV detection further supports its malicious nature.

Heuristics 8

  • URLDownloadToFile in VBA critical OLE_VBA_DOWNLOAD
    URLDownloadToFile in VBA
  • VBA URLDownloadToFile reversed-LOLBin launcher critical OLE_VBA_URLDOWNLOAD_REVERSED_LOLBIN
    VBA auto-exec macro downloads a payload with URLDownloadToFile and launches it through WScript.Shell.Exec using a reversed command string. This is a high-confidence downloader/launcher pattern, not an Office parser CVE.
  • ClamAV: Doc.Downloader.Mrkb-8213933-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.Mrkb-8213933-0
  • 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.
  • AutoOpen macro high OLE_VBA_AUTOOPEN
    AutoOpen macro
  • 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
  • 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

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
e4a3f1c97f4d6c9a3eb3c2039f61b2771b177efeb3b7f60c4c1475f6d7599043		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 4763 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
b1fda37c96367d2d80e9d8b75ad4d1aa9d5e3b8c345ccac93cc47d85b242e467		 vba-project OOXML VBA project: word/vbaProject.bin 29184 bytes
Detection
ClamAV: Doc.Downloader.Mrkb-8213933-0
Obfuscation or payload: likely
Carved macro source contains an auto-exec entry point and execution/download terms.

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