Office (OLE) / .XLSX malware analysis — malicious · 9d78608aea1bf50b

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:45:51 Authoring application: Microsoft Excel

MD5: cec8858659ad37a8fe597c383bf92e45 SHA-1: 2a0a67b660b42206a1adeddfc35277878d95ef40 SHA-256: 9d78608aea1bf50b5be44fa974a6b0d70b9d6ff1ea6daf829d3149b024850171

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1059.001 PowerShell T1569.002 Shell Execution

The sample contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical finding. The presence of dangerous formula APIs like RUN=0 indicates that the macro is designed to execute arbitrary commands. This is a common technique for downloading and executing a second-stage payload. The document body contains a large amount of seemingly random characters, which may be obfuscation or part of the macro's data.

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` `9972bae6588e2b73c323e3675660bbbfae15c43e54b06489c7abf99ef4b1149e`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6612 bytes

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