Office (OOXML) / .XLSX malware analysis — malicious · 19320c9d4c85fc5a

MALICIOUS

Office (OOXML) / .XLSX

109.3 KB Created: 2021-03-29 19:54:41 UTC Authoring application: Microsoft Excel 16.0300

MD5: 2887e4c316b45a264718708bf836cf09 SHA-1: 268ce2e7879cdcc89a72508fd382683e9cd38c51 SHA-256: 19320c9d4c85fc5ad1e33c778aec87ff842d883d0297e1b9be93f635605dc804

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 capable of executing arbitrary commands, which is a common technique for initial execution of malicious payloads. The specific commands within the macro are heavily obfuscated and truncated, preventing a more detailed analysis of the payload 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` `4ba2168210d43affdc2df39a4c02216ffe17c7afee4f75dbc3d4113362e4fe4d`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	96634 bytes

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