Office (OLE) / .XLSX malware analysis — malicious · 2773162aca3c1d9d

MALICIOUS

Office (OLE) / .XLSX

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

MD5: da7ca8d9f38edc6007b5d2ce684c6699 SHA-1: fe296f47f855b80bb21af84213d4a973470d5a03 SHA-256: 2773162aca3c1d9d709e767dbac5d367eaa510227571cb37501c3e2c45abe164

140 Risk Score

Malware Insights

MITRE ATT&CK

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

The critical heuristic OLE_XLM_AUTOOPEN_DEFINEDNAME indicates the presence of an Excel 4.0 Auto_Open macro. The OLE_XLM_DANGEROUS_FN heuristic further confirms that this macro uses dangerous functions, specifically 'RUN', which is commonly used to execute arbitrary commands. This suggests the macro is designed to download and execute a second-stage payload. No specific family could be identified.

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` `62d61c0f88d9e38053fd0093686bd5d392bc95cbd53d3acf189dae7834cf43fd`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6833 bytes

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