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

Static analysis result for SHA-256 67d2068bd503e1fa…

MALICIOUS

Office (OOXML) / .XLSM

235.5 KB Created: 2021-04-05 14:40:41 UTC Authoring application: Microsoft Excel 15.0300
MD5: 96acaf81100728d0d0423955aee109b7 SHA-1: c088c38c433d12e1655d30e9a1836c43b25e1c61 SHA-256: 67d2068bd503e1fa7efdb0a73f1e147474e5397fdee6041c6d31bcfacdba7b74
270 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1105 Ingress Tool Transfer

The critical heuristic 'OLE_VBA_HTTP_DROP_EXEC' indicates that the VBA macro downloads a file from an HTTP URL and saves it to disk, which is then likely executed. The 'OLE_VBA_OBFUSCATED_AUTOEXEC_LOADER' and 'OLE_VBA_PCODE_AUTOEXEC_EXEC' heuristics confirm an obfuscated auto-executing loader, specifically triggered by the Workbook_Open event. The embedded URLs are the most critical IOCs for this stage of the attack.

Heuristics 8

  • 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.
  • Obfuscated auto-exec VBA loader critical OLE_VBA_OBFUSCATED_AUTOEXEC_LOADER
    Auto-exec VBA reconstructs strings with a heavy custom decoder (numeric char-array, repeated hex-string decode, or junk-token Replace removal) and feeds them to a COM-instantiation or execution sink. This obfuscated-loader shape keeps CreateObject/Shell/URL indicators out of the macro source.
  • 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.
  • 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://www.you-be.jp/wp-content/plugins/seo_index/X3faiOhc3U0dyfW.php
    • https://www.ballyspringinn.com/wp-content/themes/bootcake6/lFrPXvdAemBCVs.php
    • https://gnf.fi/wp-content/plugins/seo_index/8P3V78L4u.php
    • https://octoberdawn.com/wp-content/plugins/seo_index/tFEWdLtLE.php
    • https://bigup.marketing/wp-content/plugins/seo_index/W5VmpfS30zSf2r.php
    • https://fiverworks.com/wp-content/plugins/seo_index/uDQTfI5RC.php
    • https://snow-sugar.com/wp-content/plugins/seo_index/gxQ8lhWplv.php

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
6e18ed0414d73f513c66a54632845eb13f81b05164603e8f6123131040e3cecf		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 62493 bytes
vbaProject_00.bin
91897b91741b080b18309ed6e27379c2fb1345250d2f6e8e28ef3d1628e46614		 vba-project OOXML VBA project: xl/vbaProject.bin 187392 bytes

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