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

Static analysis result for SHA-256 660a49b28334de1b…

MALICIOUS

Office (OOXML) / .XLSM

123.4 KB Created: 2021-10-27 10:31:49 UTC Authoring application: Microsoft Excel 12.0000
MD5: 02116f0284776240bbfc01174606a4cc SHA-1: 8a454864fd7d6b6f9e7d1e83ea7e8c545f101cab SHA-256: 660a49b28334de1ba4d59353a4c310501d6f3f9290b17ef6e3e3d4b6e7bc34c0
130 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution

The file contains Excel 4.0 macros that utilize dangerous functions such as FOPEN and EXEC. These functions are used to construct and execute a command that appears to download and run a payload. The specific string constructed by the macros is CHAR(67) & CHAR(58) & "\P" & "rog" & CHAR(114) & "amD" & "ata" & "\wS" & "nlr" & "" & "" & "vg" & "" & "Nl" & CHAR(78) & CHAR(114) & CHAR(111) & "Ko." & "" & "vb" & CHAR(115), which likely resolves to a path for a malicious executable.

Heuristics 4

  • 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.
  • Dangerous XLM formula APIs: FOPEN, FWRITE, FCLOSE, EXEC, RETURN critical OOXML_XLM_DANGEROUS_FN
    Excel 4.0 macro sheet uses formula APIs that call directly into Win32 (=CALL/=EXEC/=REGISTER/=FORMULA). These are the primitives used to download payloads, write files, and start processes from an XLM macro without invoking VBA.
  • Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET
    Excel workbook contains 1 hidden sheet(s) — hidden sheets are commonly used to conceal macro code, staging data, or intermediate payload construction
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL http://schemas.openxmlformats.org/spreadsheetml/2006/main
    • http://schemas.microsoft.com/office/excel/2006/main
    • http://schemas.openxmlformats.org/officeDocument/2006/relationships

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
2d2e609311087b32ccb2a6b445b7e912eb6ac33c960787730626017ec47f9ec8		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 5880 bytes

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