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

Static analysis result for SHA-256 77f6654ecab29bb4…

MALICIOUS

Office (OOXML) / .XLSM

263.1 KB Created: 2021-05-10 16:38:29 UTC Authoring application: Microsoft Excel 15.0300
MD5: 3b54f72d74244505b0b0687f3074fd31 SHA-1: 81dfc409a3f7f18528c9750ad9c6cc40ed8848a9 SHA-256: 77f6654ecab29bb4c0e3c5d1711aaec8f73fe02929d6c1c6417b0de3f457addb
310 Risk Score

Malware Insights

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

The sample is a macro-enabled Excel file containing a Workbook_Open macro that is designed to download and execute a second-stage payload. The macro utilizes `CreateObject` to instantiate objects like `MSXML2.XMLHTTP` and `ADODB.Stream` to fetch content from one of the provided URLs and save it to disk. The `rundll32.exe` command in the document body further suggests execution of downloaded content. The ClamAV detection as 'Xls.Downloader.DridexOffice0521-9863759-0' strongly indicates a downloader family.

Heuristics 9

  • VBA downloads and writes a file to disk critical OLE_VBA_HTTP_DROP_EXEC
    VBA reads an HTTP response body and writes it to disk (ADODB.Stream SaveToFile). Combined with the auto-exec/Shell paths this is a download-drop dropper even when the COM ProgIDs are built dynamically to evade keyword scanning.
  • ClamAV: Xls.Downloader.DridexOffice0521-9863759-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.DridexOffice0521-9863759-0
  • Workbook_Open macro high OLE_VBA_WBOPEN
    Workbook_Open macro
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
  • VBA p-code auto-exec with execution tokens high OLE_VBA_PCODE_AUTOEXEC_EXEC
    Compiled VBA/cache stream contains an auto-execution token together with shell/download/object-execution tokens. This catches p-code-only or source-extraction-failure macro documents where visible source is unavailable.
  • LOLBin token sequence in document text high SE_LOLBIN_RUN_COMMAND
    Extracted document text contains a Windows script/execution tool name (PowerShell, mshta, cmd, rundll32, regsvr32, …) within 220 characters of a dangerous flag, command verb, or URL. This is a visible 'run this' instruction in HTML/PDF/RTF lure bodies, or — in macro-laden Office files — the macro's own string-pool entries appearing adjacent in extracted text.
  • VBA project inside OOXML medium OOXML_VBA
    Document contains a VBA project — VBA macros present
  • Environ() call (env variable access) low OLE_VBA_ENVIRON
    Environ() call (env variable access)
  • 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 https://nellyfunerals.co.za/VKzdkfe8ufv.php
    • https://araitrade.com/dbi1vnDj.php
    • https://consultoriaemimpermeabilizacao.com/wp-includes/js/tinymce/plugins/charmap/SUn668N8oHZI.php
    • https://bay.mx/images/igfx9IW9M8o9.php
    • https://beta.hairshow.pt/Xkjfx6qv.php
    • https://kronocreativeagency.com/wp-content/themes/twentynineteen/template-parts/content/O9chyPRvQDmYt.php
    • https://aula-virtual.istpiberoamericano.edu.pe/grade/import/direct/lang/en/g1yIdqk0u.php
    • https://neatleedone.com/wp-content/plugins/bulk-attachment-download/jabd-downloads/1/ODsVQnOlgHO.php
    • https://marianayalfonso.com/wp-content/plugins/mpc-massive/panel/extra/cdJv1ZjMU3JsM.php

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
2d2e4bd7c5ca754de9da40dc2b5248c9e6bf03edc16584600f16c1e0d97c56fb		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 168170 bytes
vbaProject_00.bin
098a8d94c83d843b8d318be6ca06fa356cf2e0c9f8973832ff412720936d8dd4		 vba-project OOXML VBA project: xl/vbaProject.bin 369664 bytes

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