Office (OOXML) / .XLSX malware analysis — malicious · 20c521bf077af288

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: bb56628bec5054e9b0dc1a55e2572a63 SHA-1: 892109acb002cd2f95cf3f5c6d603207464e7539 SHA-256: 20c521bf077af288d4124e3f3bb61982591070422e5747a0787cef82083ddb6a

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The file is an Excel document containing Excel 4.0 macros, indicated by the OOXML_XLM_MACROSHEET heuristic. The macro sheet itself is heavily obfuscated and truncated, preventing a detailed analysis of its specific actions. However, the presence of Excel 4.0 macros strongly suggests an intent to execute arbitrary commands, typically for downloading and executing further malicious content. Without more discernible script content or extracted URLs, the exact payload and delivery mechanism remain unknown.

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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