Office (OOXML) / .XLSX malware analysis — malicious · db01cecbd003d5db

MALICIOUS

Office (OOXML) / .XLSX

349.6 KB Created: 2021-08-16 09:36:27 UTC Authoring application: Microsoft Excel 12.0000

MD5: fecf0782eefd4ef0d658fdc47ca98904 SHA-1: d4fea73599c37636619c5007c4a5d6232fd8195a SHA-256: db01cecbd003d5db459adaa549d3ca25786d334b0fe79c0257d537eb3eac1639

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The primary finding is the presence of an Excel 4.0 macro sheet, indicated by the OOXML_XLM_MACROSHEET heuristic. This type of macro is capable of executing arbitrary commands, which is a common technique for downloading and executing further malicious content. The macro sheet content is heavily truncated and obfuscated, preventing a more detailed analysis of its specific actions or the reconstruction of any URLs or commands. Therefore, the exact payload and delivery mechanism remain unknown.

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` `9fe47f282cb0538dcfc4044343d56e8c7917de90ef60c893e5ec9379f907a52d`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	226783 bytes

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