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

Static analysis result for SHA-256 a5b928dd8cb978aa…

MALICIOUS

Office (OOXML) / .XLSM

81.2 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 14.0300
MD5: fcd6f63bcda9b856c48efcc7ab93e102 SHA-1: a4174e10ea5dfcba41fd008959b9d20dddaf92d4 SHA-256: a5b928dd8cb978aa2ff7e93230438ccf6d12f04a62f0be677b0fb810c1e684ba
180 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic for Applications T1204.002 Malicious File T1059.001 PowerShell

The file is an XLSM document containing Excel 4.0 macros. Heuristics indicate the use of dangerous XLM functions like CALL and EXEC, which are commonly used to download and execute payloads. The embedded URL 'http://wnsx22gdouo03tuyu.xyz/grays.gif' is highly suspicious and likely serves as the source for the secondary payload. The macros are designed to download and execute a file from this URL.

Heuristics 4

  • Excel 4.0 macro sheet (3 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: FORMULA, CALL, HALT, EXEC 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.
  • 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
    • http://schemas.openxmlformats.org/markup-compatibility/2006
    • http://schemas.microsoft.com/office/spreadsheetml/2009/9/ac

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
7cc29e0426c044da329e809d130552193749e3486fd84097688f127f76120087		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 5778 bytes
xlm_sheet_01.xml
5e0b317bc9eef478a9b391aa848d4ca25c6a2921bbc6af4ad6fc140f76188572		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet2.xml 963 bytes
xlm_sheet_02.xml
98345195494abbd762f0f368955be9eed2dfec729c77fce42164df297eed179f		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 3090 bytes

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