Office (OLE) / .XLSX malware analysis — malicious · 51c33e494f8a35a2

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:41:57 Authoring application: Microsoft Excel

MD5: 456427594fc579c613f6e99bd31f5a73 SHA-1: 47cf3ef1c54336b3fafe4236e9a9a86446f8b366 SHA-256: 51c33e494f8a35a296406d030f1f15888e7e1dbaca9a20bc52339f75e15a2baa

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1059.001 PowerShell T1204.002 Malicious File

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical finding. The presence of dangerous formula APIs like RUN indicates that the macro is designed to execute arbitrary commands. This strongly suggests the macro is intended to download and execute a second-stage payload. The document body is largely unreadable, but the macro sheet itself is the primary indicator of malicious intent.

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` `22a778a16b3301889757d49970390e7527c6e0f199e946c3040bad71f52d8c37`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6494 bytes

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