IcedID — Office (OOXML) / .XLSM malware analysis

Static analysis result for SHA-256 641035efaf10eb64…

MALICIOUS

Office (OOXML) / .XLSM

338.0 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300
MD5: bb66c428fc0d6bd783ca352e1b2d85a4 SHA-1: 82ea4305840f47492e5c01d9c5095630ad8f8b80 SHA-256: 641035efaf10eb648385c5e694ac4f3a3b4cd0af75150553fb732e324b6e0b8d
310 Risk Score

Malware Insights

IcedID · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution T1105 Ingress Tool Transfer

The file contains critical heuristics indicating the presence of Excel 4.0 macros, including dangerous API calls like FORMULA and RUN, and strings related to downloading files (URLDownloadToFileA, DownloadToFileA). The macros appear to be designed to download and execute a second-stage payload using 'regsvr32' with constructed arguments. The ClamAV detection also identifies the file as 'Xls.Downloader.IcedID'.

Heuristics 7

  • Excel 4.0 macro sheet (10 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, RUN, HALT, GOTO 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.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 10 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://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 10

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
92808d2c5da41a26394309a48c8e5dea8f223f727027d3779324be19512940bd
xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 3364 bytes
xlm_sheet_01.xml
1468ac10d052bf6caa52b715a135583230c630e9863c2cc5597c81988d95f4dc
xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet2.xml 1756 bytes
xlm_sheet_02.xml
995b390512315ffed16666534397cb6932a97886fa17d78bb2d92fae83357637
xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet3.xml 2219 bytes
xlm_sheet_03.xml
9e27c63eb79aa1a21f51d99c1f994e91655cc33cf5d6d20d1646db125d4a508f
xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet4.xml 1569 bytes
xlm_sheet_04.xml
2a837d4ef451240d0866f4ac65bf8a2deb0bac7470e034180f046ef404dfd7fb
xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet5.xml 1634 bytes
xlm_sheet_05.xml
4880b2eb84be4b7a139881993b8b5f5ac9706b749d3c9b9bc743b64f1e88a030
xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet6.xml 1572 bytes
xlm_sheet_06.xml
b727b5b0e89922534aabbd5127c8e13dff5bfcde7fd64a3dc05b9dee6b4de8e3
xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet7.xml 1571 bytes
xlm_sheet_07.xml
8f2343f6b7171d70b8a27bc29094dbf44d70780c2e20fc54af7f2efd63fb1fe4
xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet8.xml 1565 bytes
xlm_sheet_08.xml
5d7c7b03d2a655edbd766182c93921d413fd7b066e3733c964ba6b88fde53057
xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet9.xml 1571 bytes
xlm_sheet_09.xml
db9aea15e28350f48db9e6e866d86c12b7aa775eb67c14d3dfbb8f7ef583b729
xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 1368 bytes