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

Static analysis result for SHA-256 ba1fa44a7c26ab42…

MALICIOUS

Office (OLE) / .XLSX

89.0 KB Created: 2020-05-20 08:20:55 Authoring application: Microsoft Excel
MD5: 0f1681a259b3afb19a30d6263e8b5821 SHA-1: 0a56279141b72297c76f2274858a4caede4cad9e SHA-256: ba1fa44a7c26ab42369949af3bea14949d01535e5e65d24f3af2c8ef0e6304a2
200 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic for Applications T1204.002 Malicious File

The file contains Excel 4.0 macros, specifically an Auto_Open macro, which is a critical finding. The macro is designed to execute dangerous functions, including the RUN function, indicating it's likely a downloader. The DOC BODY contains a partially obfuscated URL, 'http://os.mediarncbx.com/DGvqB', which is reconstructed from concatenated string fragments. This URL is highly suspicious and likely serves as the distribution point for the second-stage payload.

Heuristics 4

  • 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.
  • ClamAV: Xls.Dropper.Agent-7856657-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Dropper.Agent-7856657-0
  • 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
4e3a3d137a01aab00b12f478c14335cffea8a2c0426e313fa53689fb2cc1e90c		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 56962 bytes

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