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

Static analysis result for SHA-256 83bb22dba9fbc5b8…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-27 11:42:37 Authoring application: Microsoft Excel
MD5: 83bdf7b3a7aa9cf47993376017c5ee16 SHA-1: 610294202b049a78ff1f5afaf07d8fd1bba6ebc7 SHA-256: 83bb22dba9fbc5b8058a840126abcede26dcd8a31b66d37ae18750f26ee17cbf
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1204.002 Malicious File

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical finding. This indicates the workbook is designed to automatically execute code upon opening. The presence of dangerous formula APIs, such as RUN, suggests the macro is intended to execute arbitrary commands. While no specific download URL or payload is directly extracted, the Auto_Open functionality strongly implies a downloader or initial execution stage for a malicious 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
f230543eb69f43e97f1fb63f6f9440df9bfa6dd7b30da1f8f7489bba4e14958f
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6708 bytes