Office (OOXML) / .XLSX malware analysis — malicious · 7d34317d73e45736

MALICIOUS

Office (OOXML) / .XLSX

106.5 KB Created: 2021-03-29 19:56:22 UTC Authoring application: Microsoft Excel 16.0300

MD5: 96f287eccea6a0b49d6cf40d607c5433 SHA-1: cc5c75f2ce490aaef105467c37334f2c0a13a429 SHA-256: 7d34317d73e45736489fd832bb59154cb657bf37cabaafb039784ccf5a197338

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. While the macro content is heavily truncated and obfuscated, the presence of such macros strongly suggests an attempt to download and execute a secondary payload. The specific macro sheet file 'xlm_sheet_00.bin' is identified as the source of this malicious activity.

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` `32e4d7434e675e540915ced1066b021e6b68d176e29bfadcc879a935aa30756c`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	91649 bytes

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