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

Static analysis result for SHA-256 03cdf924eb5811fa…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:39:22 Authoring application: Microsoft Excel
MD5: ca44899486b19125c0b15fcc5f66c720 SHA-1: 280c5fb2526b0760735613fdba8be15f529a2f3c SHA-256: 03cdf924eb5811fac3fa592a527f94f0daf4ad5f58bb19ab6e7cd772de468fdc
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 indicating potential malicious execution. The presence of dangerous formula APIs like RUN further supports this. The macro sheet is designed to execute code upon opening, likely leading to further stages of an attack.

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
aeca813260724ee856510e8088e4ac528724bae61c8380869a8fa5d7fbd6097d		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6649 bytes

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