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

Static analysis result for SHA-256 0a4e60964c4016d2…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:40:58 Authoring application: Microsoft Excel
MD5: 9a1b6bcd5b7e713ad066492b67874d2e SHA-1: 758ed6d92eb81d7e5ab6703c387906a9914597a3 SHA-256: 0a4e60964c4016d27cf3888cd539db770f1f260cc7177b5e6aa00c02a0516c2d
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical finding. This indicates an attempt to automatically execute code upon opening the spreadsheet. The presence of dangerous formula APIs like RUN further suggests malicious intent, likely to download and execute 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
f8fa87e4f56f67fcd5cf9bee71aac8b956b5afd0d399fd3e73af845f7bd483bf		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6396 bytes

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