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

Static analysis result for SHA-256 d2cebe559ecad8f9…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:24:45 Authoring application: Microsoft Excel
MD5: b89017f14725d9b2c5b6fbfc02977168 SHA-1: 3224a0a0f58b2719f1e667ddd2080aa7308279dd SHA-256: d2cebe559ecad8f99033425649a0138086e654e1d9fa6abdb4f7fef7b84b847d
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

The file contains Excel 4.0 macros, specifically an Auto_Open function, which is a known technique for executing malicious code upon opening the workbook. The critical heuristic firings confirm the presence of a dangerous XLM Auto_Open formula, indicating the intent to run commands. No specific malware family could be identified, but the technique strongly suggests a downloader or initial execution stage.

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
3dd98f190c326e54abd23fc31c851f2c2e6277c13b39aebccbbe14f5a68fdea5		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6444 bytes

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