Malicious Office (OOXML) / .XLSM — malware analysis report

Static analysis result for SHA-256 bf374475be396528…

MALICIOUS

Office (OOXML) / .XLSM

160.4 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-03-14
MD5: 958c82aca0066454c7a8062c5b93c348 SHA-1: 20c1b26ddd2ae336f811bf658fbbe24c011b6393 SHA-256: bf374475be396528cdfd21a3eac292bb420e398ba9ee9ac86100f0deda916d0e
190 Risk Score

Malware Insights

MITRE ATT&CK
T1204.002 Malicious File T1059.005 Visual Basic T1105 Ingress Tool Transfer

The file is an XLSM document containing Excel 4.0 macros, which are known to be used for malicious purposes. The macros utilize dangerous functions like FORMULA.FILL and FORMULA to download a file from the reconstructed URL "http://www.bsagroup.com.br/cat.php" and save it as "C:\Datop\vima.ocx". This indicates a downloader pattern aiming to execute a second-stage payload.

Heuristics 5

  • Excel 4.0 macro sheet (9 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.FILL, FORMULA 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.
  • Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET
    Excel workbook contains 11 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 9

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
6ce4fea470c2db8d02731ed4e720a7667206a3a7a5fd5336f0d2ae7ffa98ae3d
xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 1346 bytes
xlm_sheet_01.xml
7f020f4e571d81e3d17b6813ce6a24834a18aeb2c959cfd0fdb622089ee092e5
xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet2.xml 2734 bytes
xlm_sheet_02.xml
dd54138b669223d12919e4643fb3a0eb2f62e3e1ded0c0d5af31127ebfe4f252
xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 1367 bytes
xlm_sheet_03.xml
324e5093afc39c13e777ace9df8be7faea5f692d31a4594bc698446fc92aad32
xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet2.xml 1363 bytes
xlm_sheet_04.xml
420fce9ee38179a82b2764dc98f5621f391c937061bf1f3d16890c5abf936c6d
xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet3.xml 1367 bytes
xlm_sheet_05.xml
8a8d1c4c650be80c0f9f2e14bb06ff33bab41dc920fca4ea339e5cf784812293
xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet4.xml 1364 bytes
xlm_sheet_06.xml
ff76aaecbdcb3c64c52c19fe73f5abaacc0cde572fb95fed5adc204b2f08e869
xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet5.xml 1363 bytes
xlm_sheet_07.xml
e6c5b77b0a9af449bba825200a075de48e1db4999bcd20622552c6cfac36a13b
xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet6.xml 1274 bytes
xlm_sheet_08.xml
b5b81693265ab6ec41dd278e1a16e99088c6c7e08633b16ec1b3f44dafb2f3c2
xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet7.xml 1249 bytes