Office (OOXML) / .XLSX malware analysis — malicious · 63cf7a2bff240f1a

MALICIOUS

Office (OOXML) / .XLSX

197.9 KB Created: 2021-09-20 10:27:09 UTC Authoring application: Microsoft Excel 12.0000

MD5: b27c5ea73724943b7b14ba9704c88991 SHA-1: 4d5b967b9e11003f922eeeee8e3af4ec362f395c SHA-256: 63cf7a2bff240f1ad2ea0e1d7ff4885cc174d346f04c42e6e8f6209df2acc614

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1203 Exploitation for Client Execution

The file is an Excel spreadsheet containing Excel 4.0 macros, indicated by the OOXML_XLM_MACROSHEET heuristic. These macros are capable of executing arbitrary commands, which is a common technique for downloading and executing further malicious content. The specific commands within the macro sheet are obfuscated but point towards command execution.

Heuristics 1

Excel 4.0 macro sheet (1 sheet(s)) critical OOXML_XLM_MACROSHEET

Spreadsheet contains an Excel 4.0 (XLM) macro sheet — XLM was a major Office malware vector during 2020-2022 and evaded many VBA-focused controls before Microsoft tightened XLM defaults. Even legitimate XLM use is rare in modern workbooks. The macro sheet is stored as XLSB/BIFF12 binary content, which many XML-only OOXML scanners miss.

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`xlm_sheet_00.bin` `d3d361efd35fc6a2a22e8a44a1da1e5e4a750fd748a8095388bf8fb172a68047`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	881 bytes

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