Office (OLE) / .XLSX malware analysis — malicious · c1efa5d876e2839e

MALICIOUS

Office (OLE) / .XLSX

35.5 KB Created: 2020-11-25 10:29:48 Authoring application: Microsoft Excel

MD5: 1a92b2e72684d1071588898feb9a6b2d SHA-1: 3aa887f29f33f05a9da09221c5cad5bf15900227 SHA-256: c1efa5d876e2839ecc3a8ea475e9a7a290b9dffbab6f547d35af3e09f50e544a

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1059.001 PowerShell T1059.003 Windows Command Shell

The sample contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical finding. The presence of dangerous formula APIs like RUN indicates that the macro is designed to execute arbitrary commands. While the specific commands are not fully visible due to truncation, the Auto_Open functionality strongly suggests a malicious intent to run code upon opening the document.

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` `d393a13d39314997b88b15ce101ee82034c70810f282b2225eafaef3469822fd`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6499 bytes

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