Office (OOXML) / .XLSX malware analysis — malicious · 9a60b0719e32df3d

MALICIOUS

Office (OOXML) / .XLSX

116.4 KB Created: 2021-08-16 09:36:27 UTC Authoring application: Microsoft Excel 12.0000

MD5: e8bf55ef26d48c220b838952d556b003 SHA-1: 8f78bf4cf14ac19aba19ddb82a1150145eb653d1 SHA-256: 9a60b0719e32df3d96a402f869c509ed0b630aa73ce11bfa7a0cb6e58c3a4d62

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The file is an Excel spreadsheet containing a macro sheet, identified 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, likely to download and run a secondary payload. Due to the obfuscation and truncation, the family is unknown and confidence is reduced.

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` `6772d15b5a837a0dc49915e3f5e9b5681408d5c502650eb5f17825c95684e002`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	414195 bytes

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