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

Static analysis result for SHA-256 13ad7e8dc18dc137…

MALICIOUS

Office (OLE) / .XLSX

37.0 KB Created: 2020-11-27 11:47:05 Authoring application: Microsoft Excel
MD5: caef05db236d00bd5e9587c5baafab2e SHA-1: 3b03a54995056191cd66ad0f8fdadc0a5971c5f8 SHA-256: 13ad7e8dc18dc137819e1803e14b6132cb6d6c94f4b0fd427c1a72cb0ff9f0b7
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution

The critical heuristics indicate the presence of Excel 4.0 macros with an Auto_Open entry, which is a known method for executing malicious code. The macro sheet contains a dangerous formula API, specifically 'RUN', suggesting it is designed to launch an external process or payload. The document body contains heavily obfuscated and truncated text, providing no clear user-facing lure.

Heuristics 3

  • 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.
  • 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.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
0b2d7a1b116bc62bc378c04877f8e311e2f8fb3517ea8df020c8b1a0d3a9c41e		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6984 bytes

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