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

Static analysis result for SHA-256 d1e07394af0c3a57…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-27 11:41:02 Authoring application: Microsoft Excel
MD5: 5ca0d5d504f7da8a5fca94568344c5bc SHA-1: 753e074a3b5e1eb0cb8b3df6478a4a2de0903bd4 SHA-256: d1e07394af0c3a57d7be6154181bd1198249d543d0338f4b9b2b3b2135db7b16
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1059.003 Windows Command Shell

The sample contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical heuristic firing. This indicates the workbook is configured to automatically execute a macro upon opening. The presence of dangerous formula APIs like RUN suggests the macro is intended to execute arbitrary commands. While the specific commands are obfuscated or truncated in the provided script excerpt, the overall mechanism points to a macro-based execution of malicious code.

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
ced466de58224831febbe55b885f567ffa2d4cab0b98ddb9a84a3cf25163ee7a
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6777 bytes