Office (OOXML) / .XLSX malware analysis — malicious · 3ada0070c21d2b1c

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 82ad03df6915fba52fe788dbc0d26eaf SHA-1: 0a5b2842b311cde7d912c616181c54a249424588 SHA-256: 3ada0070c21d2b1cca9a6d2facd947f358fcaada940a1b2ae7fac03a783d52d6

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The file is an Excel spreadsheet containing Excel 4.0 macros, as indicated by the OOXML_XLM_MACROSHEET heuristic. While the macro content is truncated and heavily obfuscated, the presence of Excel 4.0 macros strongly suggests an intent to execute arbitrary commands. This is a common technique for downloading and executing further malicious payloads.

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` `317840b57fa5a16653ae1674fb9ad9611fb1623ac0bed02ff55e9b262434d54b`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	7341 bytes

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