Office (OOXML) / .XLSX malware analysis — malicious · 22b0db85fd48b04f

MALICIOUS

Office (OOXML) / .XLSX

109.8 KB Created: 2021-03-29 19:55:06 UTC Authoring application: Microsoft Excel 16.0300

MD5: 61876c9fc98222705b017f94e6cef9d2 SHA-1: 1a8d1c11a1705efc34a9540320dbb3d0d543a18e SHA-256: 22b0db85fd48b04fcb5617cc13654e0c4eb27fcd8ba04ee1c5e054cde3bdbe97

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The critical heuristic 'OOXML_XLM_MACROSHEET' indicates the presence of Excel 4.0 macros. While the macro content is truncated and obfuscated, the presence of such macros strongly suggests an intent to download and execute a secondary payload, a common technique for initial access or further infection. The specific functionality cannot be determined with high confidence due to the truncated script.

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` `0d7587152bc0f528e5a96e63bf55d518f873054a6c56d73970556b76fed247db`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	94808 bytes

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