Office (OOXML) / .XLSX malware analysis — malicious · 4470d60c8c503b8f

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 4e71e77f2cde09b76e04977b79c437e0 SHA-1: f71863d8c3dd68ed51e81af6ed7b47db247cacb3 SHA-256: 4470d60c8c503b8f30aff165c39785cf95a9fe29e1b4326008361daeb11099cd

60 Risk Score

Malware Insights

MITRE ATT&CK

T1204.002 Malicious File: User Execution: Malicious Macro

The sample is an Excel 4.0 macro sheet, indicated by the OOXML_XLM_MACROSHEET heuristic. The macro sheet contains obfuscated strings that, when reconstructed, reveal a path to a file named 'excel.rtf' within the 'C:\ProgramData\' directory. This suggests the macro's purpose is to display a lure to the user, likely a fake error message prompting them to enable macros, which is a common social engineering tactic.

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` `b15a7af37e0ada47283c9101ac99d0df32a78ccc47eb9df1b66f9d296364f414`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	98647 bytes

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