Office (OOXML) / .XLSX malware analysis — malicious · e36b5edc1b66572f

MALICIOUS

Office (OOXML) / .XLSX

321.4 KB Created: 2021-08-16 09:36:27 UTC Authoring application: Microsoft Excel 12.0000

MD5: d2c657b1d893eca12b46e79b0ae908cb SHA-1: 31d2a66417a233e8c6712f661f998bf0d2f869d0 SHA-256: e36b5edc1b66572fe970f23acf55c527e91e0f31b644a5a8ce1873e6ca681286

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The file is an Excel spreadsheet containing Excel 4.0 macros, as indicated by the OOXML_XLM_MACROSHEET heuristic. These macros are capable of executing arbitrary commands, which is a common technique for initial access or payload delivery. No specific IOCs were extracted from the macro content due to its truncated and obfuscated nature.

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` `b11c5dd4e4c92e2270a47546e26d4e100a4736c3d9ecb64e9714a7f1ebdd8de0`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	426953 bytes

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