Office (OOXML) / .XLSX malware analysis — malicious · 5d678f4e868ba941

MALICIOUS

Office (OOXML) / .XLSX

82.0 KB Created: 2021-03-14 21:03:27 UTC Authoring application: Microsoft Excel 16.0300

MD5: ccc549343f05d002671d43e6a8f4252b SHA-1: 3c1e669672af9905061560116e43d59425777990 SHA-256: 5d678f4e868ba941bdac1210520972363391545d2e689a55986d9a2689b831f1

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1203 Exploitation for Client Execution

The file is an Excel spreadsheet containing Excel 4.0 macros, a known technique for executing malicious code. The macros are heavily obfuscated, but the presence of the 'xlm_macrosheet' heuristic indicates that the file is designed to run arbitrary commands. This functionality is typically used to download and execute a second-stage payload.

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` `deb177548c611b74307521e271f9ee73a3f3968e69116e07c2048af6a14bd48c`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	95567 bytes

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