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

Static analysis result for SHA-256 1329edeee1543682…

MALICIOUS

Office (OOXML) / .XLSM

196.6 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300
MD5: 7d72561c232be5c84dac3347a01f19a6 SHA-1: 8e3a62d6b1cc2181a8ca0a33141ebf215f7e3309 SHA-256: 1329edeee1543682fc17be0192ba0e95783f926259318c3a214402e5b0123dad
310 Risk Score

Malware Insights

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

This Excel 4.0 macro-enabled document (XLSM) utilizes dangerous functions like FORMULA, GOTO, and HALT to download and execute a payload. The macros contain strings for WinAPI functions such as URLDownloadToFileA, indicating an intent to download a second-stage file. The embedded script attempts to execute 'rundll32 ..\lertio.cersw' which likely points to a downloaded malicious executable.

Heuristics 7

  • Excel 4.0 macro sheet (6 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, GOTO, 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.
  • Binary XLM macro sheet with WinAPI/download strings critical OOXML_XLM_BINARY_WINAPI_STRINGS
    Excel 4.0 macro sheet is stored as BIFF12/XLSB binary data and contains Win32 download or process-execution API strings such as URLDownloadToFileA, ShellExecuteA, or CreateDirectoryA. These strings are high-signal in XLM macro sheets and catch payload-download macros that XML-formula scanners cannot parse.
  • ClamAV: Xls.Downloader.GreenEnable052-9863734-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.GreenEnable052-9863734-1
  • Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET
    Excel workbook contains 6 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://ns.adobe.com/xap/1.0/
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#
    • 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
    • http://schemas.microsoft.com/office/spreadsheetml/2014/revision
    • http://schemas.microsoft.com/office/spreadsheetml/2015/revision2
    • http://schemas.microsoft.com/office/spreadsheetml/2016/revision3
    • http://schemas.microsoft.com/office/spreadsheetml/2016/revision6

Extracted artifacts 6

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
e26278d9df62929caddc39c2675d1a93c805965a35896b4c4240468b728373e2		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 1190 bytes
xlm_sheet_01.xml
016b6b2eb925583b560ac181c148d0d9af6e5e0d9ff4bb66474d2f0161995757		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet2.xml 2846 bytes
xlm_sheet_02.xml
c627eb02b6049ab2ba980fb2219c111f1c6d4332ae6ea02091532d722ca536f0		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet3.xml 2238 bytes
xlm_sheet_03.xml
b799fe19146b2d88a059ba2f416e9e108ec4d3802659d338d7b81f2d62a387a0		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet4.xml 1463 bytes
xlm_sheet_04.xml
2606388a7d493e2de5e08d5a58acd765f1fb51cd2e623e5a4a8ae97e15cd9950		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet5.xml 1469 bytes
xlm_sheet_05.xml
f4a17b32653b96ae29aa1557978f76395ad96653818e54b0c717a27657960068		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 1476 bytes

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