Malicious Office (OOXML) / .XLSX — malware analysis report

Static analysis result for SHA-256 9ecefa4537c1daef…

MALICIOUS

Office (OOXML) / .XLSX

105.6 KB Created: 2021-03-29 19:54:15 UTC Authoring application: Microsoft Excel 16.0300
MD5: 65c76c2b58c4f58241d2d907b2e6c173 SHA-1: 030457deff0ae69dc3b890cfe5e999055e2c58c7 SHA-256: 9ecefa4537c1daef76a3ab598a3591ccb87e28f47783af3223bed5d99f4ee519
60 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

The sample is an Excel file containing Excel 4.0 macros. The heuristics indicate the presence of an XLM macro sheet, which is often used for malicious purposes. The macro sheet appears to be truncated, but the structure suggests it is designed to download and execute a second-stage payload. Due to the truncation and lack of clear indicators, the specific family is unknown.

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.

FilenameKindSourceSize
xlm_sheet_00.bin
d949a8b7ffa97589188bab8170d521758076d1b4c068e080055a6adbc7dea520		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 98782 bytes

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