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

Static analysis result for SHA-256 b31147f7ef3fb351…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:28:26 Authoring application: Microsoft Excel
MD5: af1c6ef85a39fc201ae95605323778bd SHA-1: 9849f8783ef98152be6923a11ec45a234131eab6 SHA-256: b31147f7ef3fb3510b6dfea617cc0d1aabdd56762356384b245316bcb3cd7827
140 Risk Score

Malware Insights

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

The file contains Excel 4.0 (XLM) macro sheets, specifically triggering critical heuristics for an Auto_Open defined name and the use of dangerous formula APIs like RUN. This indicates the macro is designed to execute arbitrary code upon opening. The presence of the sheet name 'QVcyQRpFRlmx' and the Auto_Open function strongly suggests a malicious intent to run a payload. While the exact payload is not directly visible, the configuration points to 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
7ff2d5216c16f8041c32b50360f289e0f57e12792a623433e3d3e1e55d114cac		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6630 bytes

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