Office (OOXML) / .XLSX malware analysis — malicious · 8b24e054f5f1c8c4

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 075e38427cd1fff3f7d2a81444ed3d60 SHA-1: 1a2e3b487e8ac9b571dda87c5a7a039e8f892528 SHA-256: 8b24e054f5f1c8c4ec4140ea8688d3a14a3e9effc512184c6b8fb66d421cfa39

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The sample is an Excel file containing an Excel 4.0 macro sheet. The macro appears to be attempting to write a file named 'excel.rtf' to the 'C:\ProgramData\' directory. This is a common technique for dropping second-stage payloads. The macro's obfuscation and the presence of a malicious verdict indicate a high likelihood of malicious intent.

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` `d2861b8489b64bd6200e2585cb3d0acca5b15c3d6bba292d5d9a19d1a3332ee7`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	104121 bytes

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