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

Static analysis result for SHA-256 063dc4a2116bad9b…

MALICIOUS

Office (OLE) / .DOC

68.0 KB Created: 2020-03-19 13:21:36 Authoring application: Microsoft Excel
MD5: a3b033f75d5637a7ca7cda6070384b02 SHA-1: 6b1514091501bb1cfd4bed30c14bc53a9d3db888 SHA-256: 063dc4a2116bad9b235b95f49f839713256657929bed3b980660b78d621bdc5d
322 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1059.005 Visual Basic T1204.002 Malicious File T1071.001 Web Protocols

The sample is an Excel 4.0 macro sheet that uses the Auto_Open function to execute. It displays a lure to enable content and then uses URLDownloadToFile to download a payload from http://owenti.com/fprl.exe. The XLM macro sheet contains references to dangerous functions like RUN and CHAR, and reconstructs a URL from cell data.

Heuristics 8

  • Reference to URLDownloadToFile API critical SC_STR_URLDOWNLOAD
    Reference to URLDownloadToFile API
  • Excel 4.0 Auto_Open defined name critical OLE_XLM_AUTOOPEN_DEFINEDNAME
    oletools recovered an Auto_Open / Auto_Close entry from an Excel 4.0 macro sheet. The raw BIFF name can be tokenized or partially opaque to byte-string checks, but the recovered macro listing confirms the workbook has an XLM auto-execution entry.
  • XLM Auto_Open with dangerous formula APIs critical OLE_XLM_DANGEROUS_FN
    Excel 4.0 macro sheet contains an Auto_Open / Auto_Close entry and dangerous XLM formula APIs that can invoke programs, write files, or transfer control without VBA.
  • URL reconstructed from XLM cell array (1 URL) critical OLE_XLM_CELL_ARRAY_URL
    Excel 4.0 macro sheet stages its payload URL across the BIFF8 Shared String Table (one quoted-char SST entry concatenated with & at runtime) or across individual numeric cells (one ASCII charcode per cell). The reconstructed URL is invisible to literal-bytes URL extraction because it is never contiguous in the workbook stream. URLs were recovered by walking the BIFF8 record stream and decoding SST entries plus LABELSST/RK/NUMBER cells.
  • Reference to ShellExecute API high SC_STR_SHELLEXEC
    Reference to ShellExecute API
  • Excel 4.0 (XLM) macro sheet present medium OLE_XLM_AUTOOPEN
    Workbook contains an Excel 4.0 macro sheet sub-stream — XLM is rarely seen in modern legitimate workbooks and was a major Office malware vector during 2020-2022.
  • Macro/content-enable lure medium SE_ENABLE_LURE
    Document instructs the user to enable macros or editing — a common technique used by malware droppers to bypass Office macro security settings
  • 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://owenti.com/fprl.exe
    • http://owenti.com/fprl.exe�
    • http://tamboe.net/frap.exe~

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
f4bb711963c94d2d1c2f5ffc8f21a42e4510b835608745d00e806bdbb3ad92c1		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 24489 bytes

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