Office (OOXML) / .XLSX malware analysis — malicious · 7fcedc1606385e92

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: f6e3899e788c2cc582d6697214d52872 SHA-1: c05d3c15e264dfe1d67db900cbeb340dc2569fa4 SHA-256: 7fcedc1606385e927f1ddbde61244cc5f7078aef22410c0a567d658ce593f3ca

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The sample is an Excel file containing Excel 4.0 macros, as indicated by the OOXML_XLM_MACROSHEET heuristic. The extracted macro content is heavily obfuscated and truncated, making it impossible to determine the exact commands being executed. However, the presence of Excel 4.0 macros strongly suggests an attempt to execute arbitrary code. Further analysis of the macro content is required to understand the full scope of the attack.

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` `cc7ab8d6fb7e1d206579115ac3f59ab8238c865fdd94ddd9732f2c40e1b42130`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	303287 bytes

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