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

Static analysis result for SHA-256 874791b8d674976a…

MALICIOUS

Office (OOXML) / .XLSX

5.52 MB Created: 2015-08-29 21:02:32 UTC Authoring application: Microsoft Excel 16.0300
MD5: eda23f12ac07a99fb6e164ad5c53ea4a SHA-1: 5732167dc8f21c7ca7c0054b6d5dc88cd61468b3 SHA-256: 874791b8d674976a87e59f843245a5e113f294cc2137369088d85921df26e2c3
370 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.003 Windows Command Shell T1204.002 Malicious File

The sample is an XLSX file containing a Workbook_Open macro, a common technique for executing malicious code upon opening. Critical heuristics indicate the use of WScript.Shell and cmd.exe, along with obfuscated VBA code, suggesting the intent to download and execute a second-stage payload. The VBA code itself appears to be a loader designed to achieve this.

Heuristics 10

  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • WScript.Shell usage critical OLE_VBA_WSCRIPT
    WScript.Shell usage
  • 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
  • cmd.exe reference in VBA high OLE_VBA_CMD
    cmd.exe reference in VBA
  • 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 http://www.truebudget.net/support.html
    • http://www.truebudget.net/learn.html
    • https://www.rondebruin.nl/mac/mac017.htm
    • http://www.rondebruin.nl/mac/mac010.htm
    • http://www.vbaexpress.com/kb/getarticle.php?kb_id=452
    • http://www.truebudget.net/support.html�
    • http://www.truebudget.net/learn.html�
    • http://www.iec.ch
    • http://schemas.microsoft.com/office/2009/07/customui
    • http://paypal.me/truebudget
    • https://www.time.gov/

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
04dc30e19277d8309181fb8a3c0adfece583a0b4a8d49726bff877a68cc855da		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 2779328 bytes
vbaProject_00.bin
39003f031475078f842bff7b07895a01da0dc2593a0b7a939ceea6d6be2b797f		 vba-project OOXML VBA project: xl/vbaProject.bin 8388608 bytes

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