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

Static analysis result for SHA-256 af650d573e62b2de…

MALICIOUS

Office (OOXML) / .XLSX

65.8 KB Created: 2021-10-27 10:31:49 UTC Authoring application: Microsoft Excel 12.0000
MD5: 23e3452617c4b801419171c675206673 SHA-1: dfcd7ea4790797fcda673f022197cf0df485fb74 SHA-256: af650d573e62b2de7fae76051b34ab07ddeaf7d844bdd4556395dcf8d25e8806
60 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

The sample is an Excel file containing Excel 4.0 macros. The macros appear to be attempting to download and execute a payload from the path 'C:\ProgramData\fnsfunsgfgnkjfsgnd'. The exact nature of the payload could not be determined due to truncation, but the intent is clearly malicious.

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
2740e6ce755ec526e9cc2716f6cee95d74774fe88d9e57adc9a847cc744fa107		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 4648 bytes

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