Office (OLE) / .XLSX malware analysis — malicious · 0c7ba4200ecf9212

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:45:58 Authoring application: Microsoft Excel

MD5: a79787e8c65e7b78fe46a53d34c367f4 SHA-1: 5732a972c1a721e695af6451ba297e50f9114c92 SHA-256: 0c7ba4200ecf921200c18236b6ec7f86a0fa2e5b5a2dc8ec7b5cf94761ad6a59

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1203 Exploitation for Client Execution

The critical heuristics indicate the presence of Excel 4.0 macros with an Auto_Open function, which is a known method for executing malicious code. The macro sheet contains a defined name for Auto_Open and uses dangerous formula APIs, including a RUN function, strongly suggesting it's designed to download and execute a secondary payload. No specific family could be identified from the available evidence.

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` `9a272b60c1e608456e4a9429139fa84d0f8b923759dc6c04faddb884eee695fa`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6689 bytes

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