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

Static analysis result for SHA-256 58fff05fa0e86643…

MALICIOUS

Office (OOXML) / .XLSX

82.3 KB Created: 2021-10-27 10:31:49 UTC Authoring application: Microsoft Excel 12.0000
MD5: bf069dde2c174c9ef630adec7e159aa9 SHA-1: fcaccb7c2ff27162a2f6d4525eec9bf35fc57ff0 SHA-256: 58fff05fa0e86643cef0ef6457c994937dd929f2ae845752b61103847730c6f4
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 sheet contains obfuscated strings that, when partially reconstructed, appear to form a path: 'C:\ProgramData\Office\version'. This suggests the macro is intended to execute a command or load a file from this location, likely as part of a multi-stage attack for payload delivery. The exact execution flow is unclear due to truncation, but the presence of Excel 4.0 macros points to a common delivery 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.

FilenameKindSourceSize
xlm_sheet_00.bin
c336ec599f4de3e805282c561a0b34d5a80486b5a80336ada0608aa4f674b3cf		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 260110 bytes

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