Office (OOXML) / .XLSX malware analysis — malicious · 11e841b5a2a390e7

MALICIOUS

Office (OOXML) / .XLSX

81.3 KB Created: 2021-02-26 07:53:41 UTC Authoring application: Microsoft Excel 16.0300

MD5: d5d70d80c230096805aa2d003fe5bf20 SHA-1: a4c46b90c0536df06b5b5bece6241f587a2f3a25 SHA-256: 11e841b5a2a390e7ce7b855f348a434c1f7cf166c09517d3beb95476ba415409

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, which are known to be used for malicious purposes. The heuristic firing indicates the presence of these macros, suggesting an attempt at initial execution of a payload. The macros themselves were truncated and heavily obfuscated, preventing a detailed analysis of their specific actions or any embedded URLs or commands.

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` `94c10f898bf35723ade4a1c59dc153e5ae9ed11a4633bd5951bbcdc3338018bf`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	4569 bytes

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