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

Static analysis result for SHA-256 576df322fb716731…

MALICIOUS

Office (OLE) / .XLSX

36.5 KB Created: 2020-11-25 10:43:07 Authoring application: Microsoft Excel
MD5: 1e389dfd6f2fd06befcfa27ed0814e25 SHA-1: 4bf3a5b7607f775a6a819388ff6339d616b7f859 SHA-256: 576df322fb71673125c0ee98abd8329f47348d9b439d1943144d6157e0e97e54
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1059.003 Windows Command Shell

The file contains Excel 4.0 macros, specifically an Auto_Open function, which is a known technique for executing malicious code upon opening the document. The critical heuristic firings indicate the presence of dangerous formula APIs within the Auto_Open macro, suggesting it is designed to run arbitrary commands. While no specific URLs or hashes were extracted, the Auto_Open macro itself is the primary indicator of malicious intent, likely serving as a loader for a secondary payload.

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
06518d7e7883961c3b63206b90ef694793de2a0e997d67696e5b6233be646aa4
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6682 bytes