IcedID — Office (OOXML) / .XLSX malware analysis

Static analysis result for SHA-256 96a44b6170402101…

MALICIOUS

Office (OOXML) / .XLSX

174.3 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300
MD5: 2c8acc9f665430546632c9b773c0fa9a SHA-1: 7e5ed9c72a5702772c8e9fd8bd27b09a935ad864 SHA-256: 96a44b6170402101b88765c52f10b9509e2b4955340bbe63c242546d6dbb3271
250 Risk Score

Malware Insights

IcedID · confidence 95%

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

The sample is an Excel file containing multiple Excel 4.0 macro sheets, including an Auto_Open macro. Heuristics indicate the use of dangerous XLM functions like FORMULA, GOTO, and HALT, which are commonly used to download and execute payloads. ClamAV detection confirms this as Xls.Downloader.IcedID, suggesting a downloader family.

Heuristics 6

  • 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.
  • ClamAV: Xls.Downloader.IcedID-9f1f1d193a2a2a2b-9951463-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.IcedID-9f1f1d193a2a2a2b-9951463-0
  • 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 — context-specific rules above attribute URLs they actually evaluated; this rule lists URLs that were present in the bytes but were not otherwise tied to a specific finding.
    URL http://schemas.openxmlformats.org/spreadsheetml/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/excel/2006/main
    • 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
11d716cf87c0994c7816faeabea3b1a2311f8469a9e654bc4a6167c25888c333
xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet2.xml 3387 bytes
xlm_sheet_02.xml
32e86c8d875e3bc28a2fb3c0512d0cffa7c2a81da63e4fe594ba2772a3b3768c
xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet3.xml 2364 bytes
xlm_sheet_03.xml
f6023b616a33da16850bd04bca335ab61b8bf9717cbe0a8ef91527cea67ae7fd
xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet4.xml 2025 bytes
xlm_sheet_04.xml
d60ca3a864e3f818e7a00f9aa3f6fdbc180e13ef9ef26c0d3de35bf633fcfa97
xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet5.xml 1560 bytes
xlm_sheet_05.xml
e39ad03223dbd59846bfcaeec79c94a8bcc60e0526ca5f2965b6b33923361cfa
xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 1831 bytes