Office (OOXML) / .XLSM malware analysis — malicious · 4a1b8d185d07ef19

MALICIOUS

Office (OOXML) / .XLSM

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

MD5: 0c9a69ab1955a93bf88d84efcb72f5a8 SHA-1: 9636e7991056dc8808b7ad74f9a3d1bc43bd4dce SHA-256: 4a1b8d185d07ef19d3dd25327fe94b1dea0fcedfa91ddd36fcf842095d4222b8

310 Risk Score

Malware Insights

MITRE ATT&CK

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

This XLSM file contains multiple Excel 4.0 macro sheets, including an Auto_Open macro, which is a common technique for initial execution. The macros utilize dangerous functions like FORMULA and RUN, and contain strings referencing WinAPI functions such as URLDownloadToFileA and DownloadToFileA, indicating the intent to download and execute a second-stage payload. The ClamAV detection as 'Xls.Downloader.IcedID' further supports this assessment.

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` `c7530dde59c603e70ce412d75426fda14e197a68cefa1761d3e6c859760fb6e5`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml	3608 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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