Office (OOXML) / .XLSX malware analysis — malicious · 4256d5d1b3325408

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 1b26e658ab5f34d9790bf28512374b86 SHA-1: fbd0a618b230fade95419534b3324921e39dc0ff SHA-256: 4256d5d1b3325408af8c2ea3f496e05d581bf1bfc45a08881f6f8d04fd26f60c

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The critical heuristic firing indicates the presence of an Excel 4.0 macro sheet. Analysis of the embedded macro reveals it attempts to create a directory and potentially download a payload to 'C:\ProgramData\fjkgdjkngfdg\fjkgdjkngfdg'. The macro is truncated, limiting further analysis of its exact behavior and payload.

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` `5beb2efc114b160a484c672ee0dd9f3a505c0d00bb60c0a81bc13b32720aa200`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	3526 bytes

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