IcedID Office (OOXML) / .XLSM malware analysis — malicious · 531da30a4a80827e

MALICIOUS

Office (OOXML) / .XLSM

335.6 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300

MD5: e377361c9fb76da5e3d93cf8e6697d8d SHA-1: 43ce32fa23d48ddf212feedd938c3043e3c1ed70 SHA-256: 531da30a4a80827e2a79f29b2775ee41b69b15ffb578c6e44836d0b6a836dc5f

310 Risk Score

Malware Insights

IcedID · confidence 95%

MITRE ATT&CK

T1059.005 Visual Basic for Applications T1204.002 Malicious File T1105 Ingress Tool Transfer

The sample is an XLSM file containing Excel 4.0 macros, which is a known delivery mechanism for IcedID. Critical heuristics indicate the use of dangerous XLM functions like FORMULA and RUN, along with strings for WinAPI calls such as URLDownloadToFileA. These functions are used to download and execute a second-stage payload, aligning with the typical behavior of 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, REGISTER, 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 — 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 10

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`xlm_sheet_00.xml` `4f1edd71b92214425488be0ab5609598e8b1470ca46787c53a8ccd9c656ce3cc`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml	3610 bytes
`xlm_sheet_01.xml` `5cf8edaadb02d80149cfaa37d2d47e8e8d2e017abafe206d2a60b0d66bf8618b`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet2.xml	2017 bytes
`xlm_sheet_02.xml` `7af916d3cd1c444b8c385b0d6b2752f132cf41445f6e98c2e7e5043d97fa2e76`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet3.xml	2705 bytes
`xlm_sheet_03.xml` `155f5ac46329f831e0bdd8c74d550d8a483e55e8697b6c1dc40c300350a39396`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet4.xml	1523 bytes
`xlm_sheet_04.xml` `9c0fa6a676553381a9c400e8fbd6d41aa5d57545dd1c4abfe88077673ac22466`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet5.xml	1796 bytes
`xlm_sheet_05.xml` `28e5eeaee4b4cd3daeca5d926f2670f953ca6120c7e677489ad69c214d0381ca`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet6.xml	1672 bytes
`xlm_sheet_06.xml` `fabdfcceeeae33f9398f720cb6160f93f2d9ae877765437d49414c7c62870108`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet7.xml	1740 bytes
`xlm_sheet_07.xml` `0765d26155c59c4df23ede3ff5621a26130db10c070b77ca40bf11501b9ab66c`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet8.xml	1684 bytes
`xlm_sheet_08.xml` `62a99322640a8d1b0f77799a63f2d9e3fa66f6fbced3622546d1c337da0e10bd`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet9.xml	1617 bytes
`xlm_sheet_09.xml` `537288100e849aad4323c1395023b8c064ba448cd71161173beafea135e8c0a2`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.xml	1667 bytes

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