Office (OOXML) / .XLSX malware analysis — malicious · 110932189dc900b1

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 2092fa46f7d5d4640ddc06b0ee16c94b SHA-1: 87b981a51da7967853e476061a50282a03a368aa SHA-256: 110932189dc900b198a1392e9c81750a87310870f31691163084ff233b0a81ca

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 capable of executing arbitrary commands, which is a common technique for downloading and executing further malicious content. The specific commands within the macro sheet are heavily obfuscated and truncated, preventing a more detailed analysis of the payload or C2 infrastructure.

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` `6b7aa18d1a0493bf8bbd92b0997e90ffc14671727c260f54ddbc28409d1b968d`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	7613 bytes

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