Formbook — Office (OOXML) / .XLSX malware analysis

Static analysis result for SHA-256 9068a52192c03433…

MALICIOUS

Office (OOXML) / .XLSX

180.6 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 12.0000
MD5: 2db157f2569512f6aa9a11d18c25dae8 SHA-1: 4adeb26c7a8bff97db252c2ae3e39455c94d6348 SHA-256: 9068a52192c03433b2726d0d7a348a1d56da1ed9e6a077b1f75420614cd7284f
168 Risk Score

Malware Insights

Formbook · confidence 95%

MITRE ATT&CK
T1204.002 Malicious File

The critical ClamAV detection and high-severity heuristics for OLE Equation Editor and CVE-2018-0798 strongly indicate exploitation of a vulnerability within the Equation Editor component. This is a common delivery mechanism for malware like Formbook, which often acts as a downloader. The embedded OLE object and anomalous native stream are key indicators of this attack vector. The presence of a hidden sheet further suggests an attempt to conceal malicious components.

Heuristics 5

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/oleObject1.bin contains the Equation Editor CLSID, the legacy component exploited by CVE-2017-11882, CVE-2018-0802, and CVE-2018-0798.
  • CVE-2018-0798 — anomalous Equation Editor native stream high CVE likely CVE_2018_0798_EQUATION_NATIVE_ANOMALY
    Embedded Equation Editor OLE data contains anomalous native stream bytes consistent with a CVE-2018-0798-style Equation Editor exploit. This is treated as likely CVE evidence because the Equation object is malformed and payload-like, but it does not match the exact public matrix-overflow byte signature.
  • ClamAV: Doc.Downloader.Formbook-bc97c1e0c33c3c93-9951465-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.Formbook-bc97c1e0c33c3c93-9951465-0
  • Embedded OLE object medium OOXML_OLE_OBJECT
    Document contains an embedded OLE object
  • Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET
    Excel workbook contains 1 hidden sheet(s) — hidden sheets are commonly used to conceal macro code, staging data, or intermediate payload construction

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
ooxml_oleobject_00.bin
1256e435f2bd1c9735d47362ec5e06377bf672c447525dc45d6b6420b3db798a		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/oleObject1.bin 4096 bytes
ooxml_oleobject_00_ole10native_00.bin
1a21f9b38de52fa863ca183a6de5dc78bb48d42347418d9f5ff177413749b112		 ole-package OOXML xl/embeddings/oleObject1.bin Ole10Native stream: OlE10NaTIve 1514 bytes
emf_00.emf
917d2f2ed70383eedd3bb6de9b4479ec30fd7cf0c32a40ea7bfe870fc2962897		 ooxml-emf OOXML EMF part: xl/media/image7.emf 1099960 bytes

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