Office (OOXML) / .XLSX malware analysis — malicious · 59253dd636251a8e

MALICIOUS

Office (OOXML) / .XLSX

71.8 KB Created: 2021-03-14 21:03:54 UTC Authoring application: Microsoft Excel 16.0300

MD5: a2f4eb67fd27ceceee347688796bf13e SHA-1: b9b2a520f485e386f158261869277b5cd2568c4c SHA-256: 59253dd636251a8e1ffd0ab7343f8cb0b2b341a205f70cc0cec35997a720366f

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The sample is an Excel file containing Excel 4.0 macros. The heuristics indicate the presence of an XLM macro sheet, which is often used to execute arbitrary commands or download further payloads. The macro content is heavily obfuscated and truncated, preventing a detailed analysis of its specific actions or IOCs. However, the presence of XLM macros strongly suggests an intent to execute malicious code.

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` `9d4e9c726d652410a5d8cd71c3a23d16daff74c567eaf8fc6145a99790a1c347`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	92099 bytes

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