Office (OOXML) / .XLSX malware analysis — malicious · 177e2a7c06bb361d

MALICIOUS

Office (OOXML) / .XLSX

104.9 KB Created: 2021-03-29 19:54:15 UTC Authoring application: Microsoft Excel 16.0300

MD5: c8e44916a4f16b757468bf18706c40eb SHA-1: 091d96f17c886740e87fc2b585dac494cf5fc581 SHA-256: 177e2a7c06bb361de849d5503134ba94aeaa16e0985521b72d78e92280a8e668

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The file is an Excel spreadsheet containing Excel 4.0 macros, indicated by the OOXML_XLM_MACROSHEET heuristic. These macros are designed to execute arbitrary code, which is a common method for initial execution of malware. The macro content is heavily obfuscated and truncated, preventing a more detailed analysis of its specific actions or IOCs.

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

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