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

Static analysis result for SHA-256 66002a2b0b0b7b5d…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-27 11:42:58 Authoring application: Microsoft Excel
MD5: 6db92342dab89c77a0bd9ec5cb2e99ea SHA-1: f31b3a3bcb107ba82ebf34f688224ce8daca7c8a SHA-256: 66002a2b0b0b7b5d878ab60ff0768e819f3d04406072a59a9c8ca13d68a8e01f
140 Risk Score

Malware Insights

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

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical indicator of malicious intent. This technique is often used to automatically execute a payload upon opening the spreadsheet. The presence of dangerous formula APIs further supports this assessment.

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
7c2e82df7dde8627f41b21c9ac9fa6810e895fe47b0b5718538c68e9d4165c33		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6855 bytes

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