IcedID — Office (OOXML) / .XLSM malware analysis

Static analysis result for SHA-256 f4afa0e9d6e4dfc6…

MALICIOUS

Office (OOXML) / .XLSM

170.9 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300
MD5: 994a37e5b3f9c1e5b82c62172ded8a21 SHA-1: 08447c474bf6ea8f1ae21f743d467f362468ac45 SHA-256: f4afa0e9d6e4dfc6afb0a5a73bac570d905e94343cfba33be6b5dcc5c0ebee5a
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 XLSM file containing multiple Excel 4.0 macro sheets. Critical heuristics indicate the use of dangerous XLM formula APIs like FORMULA, GOTO, and HALT, which are commonly used to download and execute payloads without invoking VBA. ClamAV detection confirms this as an IcedID downloader. No specific URLs were extracted, but the technique strongly suggests a downloader for a second-stage payload.

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
f6bf180283c5f2014ecc64812cad1e3a0d127b795de4593cade959ea313260e0
xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet2.xml 2896 bytes
xlm_sheet_02.xml
f29a49c753318e85f442bed44c64f292c1b7fd6c5ed8b8668c3938c69145161e
xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet3.xml 2297 bytes
xlm_sheet_03.xml
966a712c4f0f0d2f58ef2ea09ca169fd5d5278d9396ce226e09ea14a32d1074e
xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet4.xml 1477 bytes
xlm_sheet_04.xml
84368b896055b80ba37112653973d9ab4ada45ec06389956e8791ed998edcdc5
xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet5.xml 1451 bytes
xlm_sheet_05.xml
68e2eada477a01dd45889d7781ac27297df589224a5824d7ff63a37df7f5bc75
xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 1476 bytes