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

Static analysis result for SHA-256 ca70efce4de1eb0d…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:41:02 Authoring application: Microsoft Excel
MD5: 2e50ef55723690a9713843c48d04f1ff SHA-1: 07d4cdca7004f64bfe8211ecc9f78b1727afd29f SHA-256: ca70efce4de1eb0d88cc0597e4b7d92271be9d9aac023cb54d6b904654d8eb08
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell

The sample contains Excel 4.0 macros, specifically an Auto_Open function, which is a known technique for executing malicious code. The critical heuristic 'OLE_XLM_DANGEROUS_FN' indicates the use of dangerous formula APIs, including the RUN function, suggesting the macro is designed to execute arbitrary commands. The presence of the Auto_Open defined name further confirms the intent for automatic execution upon opening the document. No specific family could be identified, but the technique is common for initial access and payload delivery.

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
d538150609e97507600b19c18b141e9ac606b124aaa0b107f2619a328dd2fc96
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6490 bytes