Office (OOXML) / .XLSM malware analysis — malicious · 6c54f0f96ac51d90

MALICIOUS

Office (OOXML) / .XLSM

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

MD5: ec26a40330c9d50678253aff62e16516 SHA-1: 130fb5247ebd4c7743e9f024c06f2935e06f96ff SHA-256: 6c54f0f96ac51d9076d7b9ec0c1d4b2b27cfdbdbede38471f0df0f07e7ee46f5

310 Risk Score

Malware Insights

MITRE ATT&CK

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

This Excel file contains multiple Excel 4.0 macro sheets, which are known to be used for malicious purposes. The macros utilize dangerous functions like FORMULA and REGISTER to call Win32 APIs, specifically URLDownloadToFileA and DownloadToFileA, to download and execute a second-stage payload. The reconstructed command 'regsvr32 -s ..\Post.storg' indicates the execution of a downloaded file.

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 — 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.

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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