Office (OOXML) / .XLSX malware analysis — malicious · 3ca84e83371763b4

MALICIOUS

Office (OOXML) / .XLSX

69.1 KB Created: 2021-10-27 10:31:49 UTC Authoring application: Microsoft Excel 12.0000

MD5: 59e91382afec60999a8488a9669f3fad SHA-1: 5a74abb150f56ca71b2fcc62f60418ddb0bd0449 SHA-256: 3ca84e83371763b477791f930f80eea0d2989ace6cf7c765e90a8f4f28e893b1

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The sample is an Excel file containing Excel 4.0 macros. The heuristic firing indicates the presence of these macros, which are often used to download and execute malicious payloads. The macro content is heavily obfuscated and truncated, preventing a more detailed analysis of its specific actions or the reconstruction of any URLs or commands. Therefore, the exact family is unknown, and no specific IOCs could be extracted.

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` `4f7734dc2fa16da272428ba93a47457c1af7430f8727fe8fab94a860738a3abd`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	7403 bytes

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