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

Static analysis result for SHA-256 3533afeffc482263…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:42:29 Authoring application: Microsoft Excel
MD5: ef897732729162fe5d922e022a1d24bf SHA-1: 4264459edf899391719fce82d8af12a572923511 SHA-256: 3533afeffc482263e057a198de741a956104b9e54670ec88cf3b6a785dcfbb2e
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic for Applications T1059.001 PowerShell

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a known technique for executing malicious code upon opening the workbook. The critical heuristic firings indicate the presence of dangerous formula APIs within the XLM macro, including the RUN function, suggesting the macro is designed to execute arbitrary commands. No specific IOCs like URLs or hashes were extracted, but the presence of the Auto_Open macro is a strong 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
d2e7e90235ba51f0343559c142e6039be65a356b4f9f453754de71133732571b
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6570 bytes