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

Static analysis result for SHA-256 05a31a620437a2a6…

MALICIOUS

Office (OOXML) / .XLSX

111.6 KB Created: 2015-06-05 18:17:20 UTC Authoring application: Microsoft Excel 12.0000
MD5: e9c62c05a8997b1ac37e17830cdc724b SHA-1: 5115ce7c55f40471e2373df7888ee78982fa9fce SHA-256: 05a31a620437a2a6a7f763c5440591e66da6ad987a94e85995e16ec5e87e4b8b
260 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment

The sample is an Excel document containing a Workbook_Open VBA macro that executes obfuscated commands. The macro uses CreateObject to interact with the system, and the obfuscated commands in the document body attempt to create batch and VBScript files in C:\ProgramData. These scripts are likely responsible for downloading and executing a second-stage payload from one of the provided URLs. The ClamAV detection further confirms its malicious nature.

Heuristics 6

  • ClamAV: Doc.Malware.Valyria-10004384-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Malware.Valyria-10004384-0
  • 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
  • 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

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
527d0656a0c2c323955d068683ef8f7e20c035cda247a1e24383595c0eb3403b		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 7821 bytes
vbaProject_00.bin
be1ca39574091f7a09c66d1b3d3cf6d98e49238c05b5fa84688a46f7a0832b21		 vba-project OOXML VBA project: xl/vbaProject.bin 37888 bytes
Detection
ClamAV: Doc.Malware.Valyria-10004384-0
Obfuscation or payload: unlikely

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