Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 a96a3a6805cf900a…

MALICIOUS

Office (OOXML)

1.63 MB Created: 2016-06-27 09:21:24 UTC Authoring application: Microsoft Excel 16.0300
MD5: d94c34a797d5d3f2c35f51bc6090be3f SHA-1: f8336ad92a134a6b1dc4e0894727c689cd9a845d SHA-256: a96a3a6805cf900a884bff45289af8acae485c2de35562c876d263105f5dd3f6
230 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment T1204.002 Malicious File

The file is an Excel document containing a Workbook_Open macro, which is a common technique for executing malicious code upon opening. The macro is heavily obfuscated and uses Shell() calls, indicating an attempt to download and execute a secondary payload. The presence of hidden sheets further suggests an effort to conceal malicious activity.

Heuristics 7

  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • 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
  • 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 (hidden) low OOXML_HIDDEN_SHEET
    Excel workbook contains 10 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://www.mathsisfun.com/median.html
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#
    • http://ns.adobe.com/xap/1.0/
    • http://ns.adobe.com/xap/1.0/mm/
    • http://ns.adobe.com/xap/1.0/sType/ResourceRef#

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
f8288c0a85c102df63ea42d7acf3e737814bddd37bac5574eba12b265654482e		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 168546 bytes
vbaProject_00.bin
26e8bb6f7374e8ed95bda48423546a7674ad0c9d0a15542aeaff4a7e5ebf203b		 vba-project OOXML VBA project: xl/vbaProject.bin 663552 bytes

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