Office (OOXML) / .XLSX malware analysis — malicious · e87c0e6b253b3152

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 3397913100a0349189c38bc7657d4101 SHA-1: 41840b521437d8f6117ef29cef00ea654622c609 SHA-256: e87c0e6b253b3152a0ee46ccea13c051487d4d722a29e730c694270c295cec74

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The sample is an Excel file containing a macro sheet, indicated by the OOXML_XLM_MACROSHEET heuristic. Excel 4.0 macros are a known vector for delivering malware. While the macro content is truncated and obfuscated, its presence strongly suggests an intent to execute arbitrary code, likely to download a secondary payload. No specific family could be identified.

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` `4a73ddc9b6e25273d6e04ce1b76ac0076dea349dd352854c1ffb6bec1fa61608`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	423452 bytes

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