Office (OOXML) / .XLSX malware analysis — malicious · 7d72b56d5655b1d1

MALICIOUS

Office (OOXML) / .XLSX

60.6 KB Created: 2021-03-14 21:03:54 UTC Authoring application: Microsoft Excel 16.0300

MD5: 57e0c0017fab8f5b3ee506128e976787 SHA-1: 918056491e12dcf4b3a64e7968412b88cabfc856 SHA-256: 7d72b56d5655b1d1062664af0c19b7214087526f7904b8e0916a2d957b715f45

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, identified by the OOXML_XLM_MACROSHEET heuristic. These macros are likely designed to download and execute a secondary payload, as indicated by the embedded artifact 'xlm_sheet_00.bin'. The specific commands within the macro sheet are heavily obfuscated, preventing a more detailed analysis of its execution flow.

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` `580944619359da687e32d17b5b77125c51228921391d277987a6d801c83893d0`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	92099 bytes

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