Office (OOXML) / .XLSX malware analysis — malicious · 8ae9fa64000fe01f

MALICIOUS

Office (OOXML) / .XLSX

79.5 KB Created: 2021-10-27 10:31:49 UTC Authoring application: Microsoft Excel 12.0000

MD5: ea17fa7e465d8347ed070af0612a76d0 SHA-1: 27034ef9042fb1f984d7fbbbd3d7ca9ee8503f55 SHA-256: 8ae9fa64000fe01fd2a4df581b672d75b7fbe975a3561b6b99b2f8e14bd01225

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. The extracted macro content is heavily obfuscated and truncated, making it impossible to determine the exact commands being executed or any specific IOCs. However, the presence of Excel 4.0 macros strongly suggests an intent to execute arbitrary commands upon opening.

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` `ec187e6977b3e1b3d10d675e770a76d9dff9014c2e24318076ebb101036c45cb`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	7538 bytes

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