Malicious Office (OOXML) / .XLSX — malware analysis report

Static analysis result for SHA-256 bcd9b4f29a611792…

MALICIOUS

Office (OOXML) / .XLSX

70.3 KB Created: 2021-10-27 10:31:49 UTC Authoring application: Microsoft Excel 12.0000
MD5: aaee3dee3aa3e9e4897ae2f130e7735c SHA-1: e4ae51b2eaf99b1db050d894ca6464a235910127 SHA-256: bcd9b4f29a611792cd177f814bad8b3d3619cd26e02c1dc5f05561540790540c
60 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

The critical heuristic firing indicates the presence of Excel 4.0 macros. These macros appear to be configured to execute a command or load a file from the path 'C:\ProgramData\fnsfunSfgRgnKjFsgnd'. This suggests the file is a downloader or dropper, aiming to execute a secondary payload from a specific location on the system.

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.

FilenameKindSourceSize
xlm_sheet_00.bin
fe25f6a1b093a15ea6baab49bcc10a6b3a7f6e818f9b0915260431cf1f9abb81		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 4018 bytes

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