Office (OLE) / .XLSX malware analysis — malicious · 3f3f8fdbbededb44

MALICIOUS

Office (OLE) / .XLSX

31.0 KB Created: 2021-02-05 13:08:09 Authoring application: Microsoft Excel

MD5: d3d0fab713c4d62f0c00a790b9b820dc SHA-1: bf8220c8338aedd6ccebb735c12c20e9992e2f81 SHA-256: 3f3f8fdbbededb44bd91400f0128e43fb071d1646871f46c6589af7370b6c9dd

160 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic for Applications T1204.002 Malicious File

The sample is an Excel file containing Excel 4.0 (XLM) macros, specifically an Auto_Open macro. The document body presents a lure, instructing the user to 'Enable Editing' and 'Enable Content' to view the 'encrypted' content. The presence of the Auto_Open macro and the lure strongly indicate a malicious intent to execute arbitrary code upon opening. The XLM macros themselves contain references to potentially dangerous functions like RUN, suggesting the execution of a payload.

Heuristics 4

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.
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` `8b17334f388a6f29574d0b1c8109ade82cfe912dece2718a34a7b3b4360ebfd7`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	3326 bytes

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