Office (OLE) malware analysis — malicious · cbb3b17711d304dc

MALICIOUS

Office (OLE)

36.0 KB Created: 2020-11-25 10:46:10 Authoring application: Microsoft Excel

MD5: 25280904e7973804202f35a877db979c SHA-1: b4e181682f9a2415a604c8c7999756f0c69c4391 SHA-256: cbb3b17711d304dc4a1706c87526edde92eca3aa68d9daee09c19fee7dff1ffa

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1203 Exploitation for Client Execution

The sample is an Excel file containing Excel 4.0 (XLM) macros. The presence of an 'Auto_Open' defined name indicates that the macro will execute automatically when the workbook is opened. The critical heuristic 'OLE_XLM_DANGEROUS_FN' with 'risky-formula=3; RUN=0' suggests the macro uses functions that can execute arbitrary code, likely to download and run 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` `a1db5c38ebde058237e5602e3e04ae466a81bc756147317721f7dedb13deb90c`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6559 bytes

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