Office (OOXML) / .XLSX malware analysis — malicious · e8750ed574339c5a

MALICIOUS

Office (OOXML) / .XLSX

72.8 KB Created: 2021-10-27 10:31:49 UTC Authoring application: Microsoft Excel 12.0000 First seen: 2021-11-07

MD5: df87209e2eb623738a1bf73414aa93d8 SHA-1: 4c9ac4760626f67cf0b8ccb4229ea6fc01e03e07 SHA-256: e8750ed574339c5a54a48b74fc433ce0a41e0e1404481f9223bc75333b886b69

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The file contains an Excel 4.0 macro sheet, identified by the OOXML_XLM_MACROSHEET heuristic. The macro sheet appears to be constructing a path to a file named 'excel.rtf' within the 'C:\ProgramData\' directory. This suggests the macro's purpose is to execute commands, potentially to download and run a malicious payload from that location. The macro content is heavily obfuscated and truncated, limiting further analysis of its exact behavior.

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` `1eb814a47fd1d30f0bde52b34bc07e8208f85dac7acd87d13404894d62d39e11`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	103838 bytes

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