Office (OLE) / .XLSX malware analysis — malicious · 127671c4c8505240

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:41:30 Authoring application: Microsoft Excel

MD5: 92c3180308bb44f7a781972831fad787 SHA-1: 15b181ce0397ae2b1f6630419aae784089579634 SHA-256: 127671c4c8505240585acbcbc8d66edb9c8ec96a0fad8bfdb9a51198510cc59c

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1203 Exploitation for Client Execution

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a known technique for executing malicious code upon opening the workbook. The presence of dangerous formula APIs like RUN indicates an intent to execute arbitrary commands, likely to download and run a second-stage payload. No specific family could be identified, but the technique is common for initial execution.

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` `25dad65a71f9aed3bb529a27b741fda1245778f7f0f872aba4e028e9b7df6d31`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6515 bytes

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