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

Static analysis result for SHA-256 7a99a0e0517b6881…

MALICIOUS

Office (OOXML) / .DOCM

16.4 KB Created: 2020-10-25 16:26:00 UTC Authoring application: Microsoft Office Word 15.0000
MD5: 87d0d8864689715d51d73735a90d5aef SHA-1: be3bc339099ef1e5ba627994465a305c975504db SHA-256: 7a99a0e0517b6881ac79986fdad2507454acba4cb3218c1378d2cf8585d9fbb0
382 Risk Score

Malware Insights

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

The sample is a macro-enabled Word document (DOCM) that contains an auto-executing Document_Open macro. This macro is obfuscated and uses Shell() and CreateObject() to download a VBScript payload from the URL "http://www.4shared.com/file/PdyLpTk1iq/Purchase_Order.html", save it as "K8z.VBS", and then execute it. The script also attempts to establish persistence by writing to the registry key "HKCU\Software\Microsoft\Windows\CurrentVersion\Run\IAccessible2Proxy".

Heuristics 9

  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • Obfuscated VBA Shell command with URL critical OLE_VBA_OBFUSCATED_SHELL_URL
    VBA macro invokes Shell with command text assembled through decoder or string-manipulation functions and includes a URL. This is a high-confidence downloader/dropper pattern, stronger than Shell or URL evidence on their own.
  • 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.
  • Document_Open macro high OLE_VBA_DOCOPEN
    Document_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
  • 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.microsoft.com/office/word/2010/wordprocessingCanvas
    • http://schemas.openxmlformats.org/markup-compatibility/2006
    • http://schemas.openxmlformats.org/officeDocument/2006/relationships
    • http://schemas.openxmlformats.org/officeDocument/2006/math
    • http://schemas.microsoft.com/office/word/2010/wordprocessingDrawing
    • http://schemas.openxmlformats.org/drawingml/2006/wordprocessingDrawing
    • http://schemas.openxmlformats.org/wordprocessingml/2006/main
    • http://schemas.microsoft.com/office/word/2010/wordml
    • http://schemas.microsoft.com/office/word/2012/wordml
    • http://schemas.microsoft.com/office/word/2010/wordprocessingGroup
    • http://schemas.microsoft.com/office/word/2010/wordprocessingInk
    • http://schemas.microsoft.com/office/word/2006/wordml
    • http://schemas.microsoft.com/office/word/2010/wordprocessingShape
    • http://www.4shared.com/file/PdyLpTk1iq/Purchase_Order.html

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
c39b3f3ae6a0858dea380078d52b05338958bef9cb5a956e4b6d7230b76564f1		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 2077 bytes
vbaProject_00.bin
84df2a1043dac4b136f4cdf2675b603cf00b646fa0e05d2c4ee0d0bcb4249f7f		 vba-project OOXML VBA project: word/vbaProject.bin 11776 bytes

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