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

Static analysis result for SHA-256 7000ccf79a48e2ce…

MALICIOUS

Office (OOXML) / .XLSM

247.7 KB Created: 2021-08-16 09:36:27 UTC Authoring application: Microsoft Excel 12.0000
MD5: 53f4946c0b637e6feaa17038259ae084 SHA-1: 6cd474d9055b169b6b6df59e2ff69e303e5d4e0d SHA-256: 7000ccf79a48e2ce15eb3c46a0c56e9cdccbc917de56b279dab3514fc1f80d2a
190 Risk Score

Malware Insights

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

The file is an XLSM document containing Excel 4.0 macros, which are known to be used for malicious purposes. The macros utilize dangerous functions like EXEC and FOPEN to write and execute a script file located at C:\ProgramData\lzewtfo.sct. This indicates the sample's primary function is to download and run a second-stage payload.

Heuristics 5

  • 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.
  • Excel 4.0 Auto_Open defined name critical OOXML_XLM_AUTOOPEN_DEFINEDNAME
    Workbook defines _xlnm.Auto_Open or _xlnm.Auto_Close while containing an XLM macro sheet. This is the OOXML/XLSB auto-execution shape for Excel 4.0 macros.
  • Dangerous XLM formula APIs: FOPEN, FWRITE, FCLOSE, EXEC, HALT 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
524b7ede65233258db9be6ab8ff9f54a402f9035a7db3a976a92da4d0666f00f		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 697642 bytes

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