Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 bb66897475661ec8…

MALICIOUS

Office (OOXML)

440.8 KB Created: 2019-10-01 12:18:50 UTC Authoring application: Microsoft Excel 14.0300
MD5: 63f4c67ff10ab30fee20cf3119a36a43 SHA-1: b317391513246262533a03dbb2d878d72691203d SHA-256: bb66897475661ec865f41e3e552a0a86155d4c2897c140bab729dbb7513a5a06
370 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File T1071.001 Web Protocols T1059 Command and Scripting Interpreter

The sample is a macro-enabled Excel document containing a Workbook_Open macro that is heavily obfuscated. This macro utilizes CreateObject and Shell calls to download and execute a second-stage payload from an external URL. The presence of these critical heuristics indicates a clear intent to download and run malicious code, likely leading to further compromise.

Heuristics 10

  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • 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
  • GetObject call high OLE_VBA_GETOBJ
    GetObject 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
  • Hidden worksheet (veryHidden) low OOXML_HIDDEN_SHEET
    Excel workbook contains 3 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 https://github.com/VBA-tools/VBA-JSON
    • http://www.vbaccelerator.com/home/VB/Code/Techniques/RunTime_Debug_Tracing/VB6_Tracer_Utility_zip_cStringBuilder_cls.asp
    • https://github.com/VBA-tools/VBA-JSON/pull/82
    • https://github.com/VBA-tools/VBA-UtcConverter
    • http://www.opensource.org/licenses/mit-license.php
    • http://code.google.com/p/vba-json/
    • http://msdn.microsoft.com/en-us/library/windows/desktop/ms724421.aspx
    • http://msdn.microsoft.com/en-us/library/windows/desktop/ms724949.aspx
    • http://msdn.microsoft.com/en-us/library/windows/desktop/ms725485.aspx
    • http://support.microsoft.com/kb/269370
    • http://www.ietf.org/rfc/rfc4627.txt
    • https://support.microsoft.com/en-us/kb/272138
    • https://rseds.eaeunion.org/api/registry?classifier=APPLIED&limit=1&page=0&text=R.022
    • https://rseds.eaeunion.org/api/registry/download/xsd/
    • http://www.opensource.org/licenses/mit-license.php)�
    • http://msdn.microsoft.com/en-us/library/windows/desktop/ms725485.aspx�
    • https://support.microsoft.com/en-us/kb/272138����

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
41b85ad89f7cb60aad7b2af8f0201d5f4ee69abc9e6dfdf5be71f066f5512a90		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 260564 bytes
vbaProject_00.bin
98adc4c4e9c24b126ddb695d56de83e584132daf8b0dae9cb67c4d9b459d0ee4		 vba-project OOXML VBA project: xl/vbaProject.bin 846336 bytes

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