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

Static analysis result for SHA-256 4f5a757b637da1ef…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-27 11:38:51 Authoring application: Microsoft Excel
MD5: 20809d21621769c1720fc9f39b40a7fe SHA-1: a0d21eeb6af6c736da298770020ed07b145711e4 SHA-256: 4f5a757b637da1efb2245bed30918afab2d2417f9311cb01cc9186bad7dfebb5
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment

The file contains Excel 4.0 macros, specifically an Auto_Open function, which is a critical finding. This function is designed to execute arbitrary commands upon opening the workbook. The presence of 'RUN=0' in the heuristic firing indicates the macro is capable of executing external programs. While no specific URLs or hashes were extracted, the Auto_Open macro is a strong indicator of malicious intent, likely for downloading and executing a second-stage 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
2ba8651e78acec969dd8aaf1e4095f63ef7dbf9b0e5131291032f9cbbfe7378b
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6664 bytes