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

Static analysis result for SHA-256 718cca0f792d1043…

MALICIOUS

Office (OLE) / .XLSX

36.5 KB Created: 2020-11-25 10:41:28 Authoring application: Microsoft Excel
MD5: fd8cf39d1847d2e4a35dbce33fd95a4a SHA-1: a495149b6ab4b8ce856e700a62d4b28de4b46f87 SHA-256: 718cca0f792d1043f7009ffc5fa4ba74e467abc33a13cbe75bee10ed3c48fca7
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical finding indicating automatic execution upon opening. The presence of dangerous formula APIs like RUN further suggests malicious intent. This points to a macro-based attack, likely delivered as a spearphishing attachment, designed to execute arbitrary code.

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
39df9fde062c0ab20914df621544559f2c8c31fb56046a059f85d1e624147861		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6623 bytes

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