Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 f7918cdf63b75055…

MALICIOUS

Office (OOXML)

10.97 MB Created: 2015-02-09 17:54:36 UTC Authoring application: Microsoft Excel 16.0300
MD5: f48884087f5072c5580dade3df008286 SHA-1: 66fdb77e4fde190d879ec44e3569433838180c67 SHA-256: f7918cdf63b750553ddb45fb336d66436f2074696754b242e4a07aeaae6be40c
538 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File Execution: Malicious Script T1059 Command and Scripting Interpreter

This Excel document contains a Workbook_Open macro that is obfuscated and uses WScript.Shell to execute a command. The macro is designed to download and execute a second-stage payload from the URL http://pixcels.nl/set-activeprinter-excel. The presence of obfuscated VBA, Shell() calls, and WScript.Shell usage strongly indicates malicious intent.

Heuristics 14

  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • WScript.Shell usage critical OLE_VBA_WSCRIPT
    WScript.Shell usage
  • 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.
  • 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.
  • ClamAV detection on extracted artifact critical EXTRACTED_FILE_CLAMAV
    ClamAV flagged at least one file extracted from inside this sample. Even when the wrapping document carries no AV detection of its own, a hit on the carved artifact is a strong indicator the sample is a delivery vehicle.
  • 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
  • External relationship high OOXML_EXTERNAL_REL
    External target in xl/externalLinks/_rels/externalLink1.xml.rels: file:///\\la-y-wb-srv-1\temp\PandEDev\XLS\Total_Compensation.xlsm
  • 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)
  • Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET
    Excel workbook contains 2 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 http://pixcels.nl/set-activeprinter-excel
    • http://blogs.msdn.com/b/alejacma/archive/2008/04/11/how-to-read-a-registry-key-and-its-values.aspx
    • http://www.experts-exchange.com/Software/Microsoft_Applications/Q_27566782.html

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
659328a6b3510651766e3ecf0cf42afcd14b7dd97f8a0a87472ec3857b616164		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 307559 bytes
vbaProject_00.bin
8563ce05a1a7646b95fceefba3501e19bbe98da11d2bd60d46f28ee4a6915d36		 vba-project OOXML VBA project: xl/vbaProject.bin 522752 bytes
Detection
ClamAV: Xls.Macro.Obfuscation-9804250-0
Obfuscation or payload: unlikely

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