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

Static analysis result for SHA-256 6d5f1ee21cb36801…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:44:47 Authoring application: Microsoft Excel
MD5: d9e3a1a93952797ba1362f03fd8db6cd SHA-1: 93930f6d99184ad2759948ff22d25d5addf53def SHA-256: 6d5f1ee21cb36801dfa8ec70553e1abaa030c92194e3ae5847a58d1d431c8839
140 Risk Score

Malware Insights

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

The critical heuristics indicate the presence of Excel 4.0 macros with an Auto_Open defined name, which is a known technique for executing malicious code upon opening the workbook. The macro sheet contains a reference to 'Auto_Open', suggesting it will attempt to run code automatically. This is a common method for delivering secondary payloads.

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
dcf8753f7083a7fed710a76d1778bd3c2c3de26a0b5d2f42018a600860994e39		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6422 bytes

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