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

Static analysis result for SHA-256 5c9381ac666a1efa…

MALICIOUS

Office (OOXML) / .XLSX

111.6 KB Created: 2015-06-05 18:17:20 UTC Authoring application: Microsoft Excel 12.0000
MD5: 78f55b274208717f3f89dbc03aef1ca6 SHA-1: e12ee158a27d3ec60cf53388ca69c5eb1aedad64 SHA-256: 5c9381ac666a1efaf571d68b94e1e354d25e2cac64d03c4ee44f6b9396b0e55b
260 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment T1105 Ingress Tool Transfer

The file is an Excel document containing a Workbook_Open VBA macro. This macro is designed to execute a command that downloads a batch file and a VBScript from a series of hardcoded URLs. The VBScript is then executed, likely to download and run a second-stage payload. The ClamAV detection 'Doc.Malware.Valyria-10004384-0' further supports 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
c3d1148f2c2698a8693ec937f18fe70c72dab5b6dcb1f92676438abb9274ac41		 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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