Office (OLE) / .XLS malware analysis — malicious · 10a69a941a603492

MALICIOUS

Office (OLE) / .XLS

42.5 KB Created: 2020-10-19 11:05:02 Authoring application: Microsoft Excel

MD5: 040d9eeb72c60d9a2dadb3506e5f1e5c SHA-1: 1eea1b630a1d9461c2c9d92aa9b5104cca5b1df7 SHA-256: 10a69a941a6034922bc4973704927bfeca8770620f2dabde673df3910a85dc05

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1203 Exploitation for Client Execution

The file is an Excel 4.0 macro-enabled workbook containing an Auto_Open defined name, which is a critical finding indicating automatic execution upon opening. The macro sheet uses dangerous formula APIs, specifically 'RUN', suggesting it is designed to execute arbitrary commands. This points to a downloader or dropper functionality, where the macro is used to fetch and execute a secondary malicious payload.

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` `7412fd9d4854df2945f70f1f15452ea1b9217f4baa039768357f43669b22f062`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	9083 bytes

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