Office (OOXML) / .XLSX malware analysis — malicious · 7afea17a13f2dd18

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: dc0fd795acd135a66520283eecf4ad32 SHA-1: 7137dd36df75924cc1668e12e805429163673418 SHA-256: 7afea17a13f2dd18c6762a60738e47a4cf999965b444ae9a841b444e14ae72b4

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The critical heuristic firing indicates the presence of Excel 4.0 macros within the XLSX file. These macros are known to be used for executing arbitrary code, often to download and run additional malicious content. The truncated script content prevents a more detailed analysis of the specific actions taken, but the presence of XLM macros is a strong indicator of malicious intent.

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` `70edfd918f46a98a0301578a3a15b6e9bb1d2573440766c550d6d3b1a216a1cb`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	231186 bytes

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