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

Static analysis result for SHA-256 7efb36c0526438e7…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:40:46 Authoring application: Microsoft Excel
MD5: 98ec9a8d1f7c4ca4cc40e94bbda2a776 SHA-1: 5b3b50bf621236d6cf8af4f8e21e736d7667ee9d SHA-256: 7efb36c0526438e742767d461cbf9b64f9b08067e2bd11fb0545c95ddf696c08
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 macros, specifically an Auto_Open defined name, which is a critical finding. The heuristics indicate the use of dangerous formula APIs, including the RUN function, suggesting the macro is designed to execute arbitrary commands. This is a common technique for initial payload delivery in macro-based attacks. No specific family could be identified, but the execution of the Auto_Open macro is the primary indicator of malicious intent.

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
38e8ae6bbf7fe40b6f0e4c5b9756394ade195dc59cf45418b529209087c5b5bf
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6458 bytes