Office (OOXML) / .XLSX malware analysis — malicious · b95870ca4d00f822

MALICIOUS

Office (OOXML) / .XLSX

274.1 KB Created: 2021-10-04 08:20:54 UTC Authoring application: Microsoft Excel 12.0000

MD5: 740a0b7b476ac3131083e22d6ed09668 SHA-1: 1cf4f161424c9b8a945458c36e12e16ff433966d SHA-256: b95870ca4d00f82239045b3d770322e17071fbed24644d5702be98f75b6bd4b5

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The file is identified as an Excel 4.0 macro sheet, which is a known method for executing malicious code. While the specific macro content is truncated and obfuscated, the presence of an XLM macro sheet strongly suggests an intent to run arbitrary commands upon opening. No specific family could be identified due to the limited script visibility.

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` `aed43ec046179db02edce7523610e720511222005b2938253321978ff3ea7084`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	999141 bytes

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