Office (OLE) / .XLSX malware analysis — malicious · b255b171c5ecb64f

MALICIOUS

Office (OLE) / .XLSX

77.0 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel First seen: 2022-05-25

MD5: dd8a7b9b27f053cb19396517c1170e8a SHA-1: ebdb72a4ea8b9834334613bb3c510c21122d3944 SHA-256: b255b171c5ecb64f64163421b84e69b1be55315854e701c3b8fe892b245f0384

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1204.002 Malicious File

The file contains Excel 4.0 macros, specifically an Auto_Open macro, which is a critical indicator of malicious intent. The macro is configured to execute dangerous functions, including the RUN function, suggesting it's designed to download and execute a second-stage payload from one of the provided URLs. The presence of multiple suspicious URLs further supports this conclusion.

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` `2ca0966e93dacad101ceb18f4d58731b5432892fe851526f2fda59486181312c`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	7325 bytes

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