IcedID — Office (OOXML) malware analysis

Static analysis result for SHA-256 fffb8b682a7635db…

MALICIOUS

Office (OOXML)

186.6 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300
MD5: a4a8c61535aba8136775076a1e64a386 SHA-1: 8380e5732cfb0f705b74511657169999c182ca51 SHA-256: fffb8b682a7635db701ba67d6b198990dffc5ecc21425efba19f7ef6041ce80b
242 Risk Score

Malware Insights

IcedID · confidence 95%

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

The file contains Excel 4.0 macros that utilize dangerous functions like CALL and EXEC to download a payload from 'http://feedbackfile.today/big.php'. The macros then attempt to execute the downloaded file, identified as '..\NACHILE2.dll', using 'regsvr32 -silent "..\NACHILE2.dll"'. This behavior is characteristic of the IcedID malware family, which often uses macro-enabled documents as a downloader.

Heuristics 5

  • 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 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.
  • ClamAV: Xls.Downloader.IcedID-9f1f1d193a2a2a2b-9951463-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.IcedID-9f1f1d193a2a2a2b-9951463-0
  • 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://feedbackfile.today/big.php
    • 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
e9d97d649b34346bcb4bd0af3ec29988fb7110472ea624571a0deab2bf2ddcf0		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet2.xml 1008 bytes
xlm_sheet_01.xml
ee5b04b8f330ce3b38b1a1c9ced2c24cbcea9c511e23ef82cbed8244f2af6f15		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 1389 bytes
xlm_sheet_02.xml
d5692bc5ce8070c4b9377e31129ace6dfc890572ab59d199fb9e9bd516cb016f		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet3.xml 1659 bytes

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