Office (OLE) / .XLSX malware analysis — malicious · 235e6bb9f82df21f

MALICIOUS

Office (OLE) / .XLSX

41.5 KB Created: 2020-11-13 16:10:11 Authoring application: Microsoft Excel

MD5: 192d9ecdd1180248632b316298a179ae SHA-1: e50c81f208a02f1f73e059d91e68012d06246dd2 SHA-256: 235e6bb9f82df21fa0c243cbc53efc4d2079e4ea1bf2d316600938b2e619ee68

140 Risk Score

Malware Insights

MITRE ATT&CK

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

The file contains Excel 4.0 macros, specifically an Auto_Open function, which is a critical finding. The presence of 'RUN=0' within the macro indicates a dangerous function call, likely intended to execute arbitrary code. This strongly suggests the macro is designed to download and execute a secondary payload. No specific family could be identified, but the technique is common for initial access.

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` `a2abe42f1ec6f644077ef6f41e277349164b52e6d5fb5202fb994548aabf305d`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	9361 bytes

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