Office (OOXML) / .XLSX malware analysis — malicious · 2b154b5f67c1e4c8

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 72837f097fb8e21abf06caf4851e34f2 SHA-1: 0370da88507e399ce082b3f51f2a74fe05613fd0 SHA-256: 2b154b5f67c1e4c873cfa92e3fc9c9c4a170549b47f643e349949013477cdcb6

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The file is an Excel 4.0 macro sheet, identified by the OOXML_XLM_MACROSHEET heuristic. The embedded macro sheet contains obfuscated commands that appear to construct file paths and execute them. Specifically, it constructs the path 'C:\ProgramData\a\a\a\a\a\bQ\MW.r t' which is likely intended to download and execute a second-stage payload. The macro's obfuscation and command execution suggest a downloader or initial access mechanism.

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` `210b2c8127c1644ec20934a603f70ac00352918fb4658bcd3e18a658d117bc6e`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	5015 bytes

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