Office (OOXML) / .XLSX malware analysis — malicious · 98f655b81232dc9c

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: d6cef9a209360d2f38ee934b12064fdc SHA-1: eadd29152e7e7916bb01e294d967dd0e2e68def5 SHA-256: 98f655b81232dc9c1cbf0b659a79670396d52a2575ada7821db39f88c14e128e

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The sample is an Excel file containing Excel 4.0 macros, indicated by the OOXML_XLM_MACROSHEET heuristic. While the macro content is truncated and heavily obfuscated, the presence of XLM macros strongly suggests an attempt to execute arbitrary commands. This is a common technique for initial payload delivery in macro-based attacks. No specific family could be identified due to the limited script content.

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` `a270d236c4f55c61e0f310f9fb99f1bebf228d151997210e3bab7b0bb37d9dfd`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	7682 bytes

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