Office (OOXML) / .XLSX malware analysis — malicious · 19b14e5f0e4c6b81

MALICIOUS

Office (OOXML) / .XLSX

84.8 KB Created: 2020-11-16 23:24:40 UTC Authoring application: Microsoft Excel 16.0300

MD5: fc19e502cee0d72880aadb86f1123844 SHA-1: f5a795e84224afcaa29cee0d681178789ecf92b8 SHA-256: 19b14e5f0e4c6b81126531e5b916017fab951b709b2f8f30056c5be1bed1d5ce

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1204.002 Malicious File

The file is an Excel 4.0 macro sheet, identified by the OOXML_XLM_MACROSHEET heuristic. The embedded XLM macro code, though truncated, strongly suggests it is designed to download and execute a secondary payload. This is a common technique for delivering malware.

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` `f55519a4393b01d7e89f15552e1e38ad448f50302046d4d07093fabb295a050c`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	27531 bytes

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