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

Static analysis result for SHA-256 8fa13a30c610528e…

MALICIOUS

Office (OLE) / .XLSX

36.5 KB Created: 2020-11-30 17:47:55 Authoring application: Microsoft Excel
MD5: e72c93efc79c10847f8a3284f294495b SHA-1: c5500b41d71a527fce87a713861cebe9b9b5b4e8 SHA-256: 8fa13a30c610528e3dfa807d8a8bceb67393f35fae3a11edcd35d9f0a6aff0d3
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. This indicates the workbook is designed to automatically execute code upon opening. The presence of dangerous formula APIs like 'RUN' further confirms the malicious intent to execute arbitrary commands. While the specific payload is not directly visible, the Auto_Open macro is a common technique for delivering second-stage malware.

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
6dbb499f9c0c89d129eac38cdd91559ed3b7a6bdf55b4ce87afebe0d01cd669f
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6807 bytes