Office (OLE) / .XLSX malware analysis — malicious · 173b70e3cbc9ca8b

MALICIOUS

Office (OLE) / .XLSX

316.5 KB Created: 2020-05-20 11:27:16 Authoring application: Microsoft Excel

MD5: 4c0269cf81144f6fddfd2db85f577b24 SHA-1: a1ebf2fff596f88199a7e2adc1388e806010f151 SHA-256: 173b70e3cbc9ca8be9396de95bf9ed5d24609478345c5fbb8cb62333f72a9b63

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The critical heuristics indicate the presence of obfuscated Excel 4.0 (XLM) macros with an Auto_Open execution chain. This suggests the file is designed to automatically run malicious code upon opening. No specific URLs or further payloads were extracted, limiting the ability to identify the exact family or further IOCs.

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.
Obfuscated XLM Auto_Open execution chain critical OLE_XLM_OBFUSCATED_AUTOEXEC_CHAIN

Excel 4.0 macro sheet contains an Auto_Open / Auto_Close entry and an obfuscated formula execution chain. The macro builds strings through FORMULA(CHAR(...)), primes state with SET.VALUE / GET.CELL / GOTO, and transfers control through RUN(). This is a high-confidence XLM malware pattern.
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` `68e020e151bbf19edb32043639f992430a4ff4b0d0d6bcfc8fde1a40e76cdaed`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	125655 bytes

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