Office (OLE) / .XLSX malware analysis — malicious · 7241a58ac6c57f09

MALICIOUS

Office (OLE) / .XLSX

36.5 KB Created: 2020-11-27 11:43:17 Authoring application: Microsoft Excel

MD5: 65b235f5b1fac240696e289d01648c7a SHA-1: 7acb85ada88531461b9d3be7f6caf5e6ae6d5969 SHA-256: 7241a58ac6c57f092518499227ca9871c31149dca3b6e6ee33a1d89fe6b76210

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 for arbitrary code execution. The presence of dangerous formula APIs like RUN further supports this. The macro sheet itself contains obfuscated strings and data, suggesting it's designed to perform malicious actions, likely downloading and executing a secondary 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.

Filename	Kind	Source	Size
`xlm_macros.txt` `b9b73e92b038399711ccb0c7f75971b43c6c971cd84cfb03ba42bc5b997a7820`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6680 bytes

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