Office (OOXML) / .XLSX malware analysis — malicious · c561621bfed227ee

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: d1b6eaf726b793396f77b695e2e1d06d SHA-1: b4de86dc4f386852d712ddc8ec9f1c6057c7827e SHA-256: c561621bfed227ee5db9c9d5ef54a90b5bbdddb227111914e7554c5aac8261a1

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The file is an Excel spreadsheet containing Excel 4.0 macros, as indicated by the OOXML_XLM_MACROSHEET heuristic. The macro code appears to be attempting to write a path to the ProgramData directory, likely to stage a downloaded payload. The script is truncated, preventing a full analysis of its execution flow, but the presence of macros and the staged path strongly 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` `165a5714cb0c126b0426a396dae2e6c56aea39c862c08deaa510f653c6bf9626`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	4160 bytes

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