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

Static analysis result for SHA-256 3be00f841aaa333d…

MALICIOUS

Office (OOXML) / .XLSX

98.2 KB Created: 2021-10-27 10:31:49 UTC Authoring application: Microsoft Excel 12.0000
MD5: ec771f1ae6466858e6e318dba31ad179 SHA-1: e9cf6f6fb58029cfef4f9a01b39dd564d827248d SHA-256: 3be00f841aaa333d92a6aea4ea5955ad98fc9a5be92a441e6921e356f9982b60
60 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

The critical heuristic firing indicates the presence of an Excel 4.0 macro sheet. The macro sheet contains obfuscated strings that, when reconstructed, appear to form a path to a file named 'excel.rtf' within the 'C:\ProgramData\' directory. This suggests the macro is intended to execute or drop a malicious file from this location, likely as a first-stage downloader.

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
92163040b8e3414fa7bc67d5c22c3f0c23eba6b8d54384143ba7acf80558b76c		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 159232 bytes

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