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

Static analysis result for SHA-256 f83e18451534295d…

MALICIOUS

Office (OLE) / .XLSX

36.5 KB Created: 2020-11-27 11:42:07 Authoring application: Microsoft Excel
MD5: 1588812cdab4a15c7dbf5b0c3f928d1b SHA-1: 6445524eda95dce583b75f3acb18d29fea1fbe76 SHA-256: f83e18451534295d6b08ca61c82efb307362af11ffdaca2474ad1b2e31f94fa4
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 defined name, which is a critical finding. This indicates that the macro sheet is designed to execute automatically when the workbook is opened. The presence of dangerous formula APIs, including the RUN function, suggests that the macro is intended to execute arbitrary commands. While no specific URLs or hashes were extracted, the Auto_Open functionality is a strong indicator of malicious intent, likely to download and execute 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
94d89a1e392338e4a7f1feedf6f514a46be3d2002dd3b15242f2454863237cf2
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6683 bytes