Office (OOXML) / .XLSX malware analysis — malicious · 2a7fadfd79294f90

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 923db97bea22784bdddeed9fcd41ae11 SHA-1: 21711688a78dd659029ef20ff169e2304163ee36 SHA-256: 2a7fadfd79294f9046067dafdef3e9eeb38a3e46461749c1f12d11d7c84f60d3

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The file is an Excel spreadsheet containing embedded Excel 4.0 macros. The critical heuristic firing confirms the presence of these macros, which are often used to download and execute additional malicious payloads. The macro content itself is heavily obfuscated and truncated, preventing a more detailed analysis of its specific actions or the reconstruction of any URLs or commands. Therefore, the exact family and IOCs cannot be confidently determined.

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` `c4050efac02add1cf907348ae14cd379a3ee62c1c64718fb61eb86165d0039aa`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	6987 bytes

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