Formbook — Office (OOXML) / .XLSX malware analysis

Static analysis result for SHA-256 aea063044c0abfdf…

MALICIOUS

Office (OOXML) / .XLSX

180.8 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 12.0000
MD5: 92b04cbe0658f9be51553e4516d12643 SHA-1: ba76905731d071ec5e98cb7149cc8f081a70d77c SHA-256: aea063044c0abfdf9fdb812d0b59a3aa3c23f7ed4421af373e34bad6c113595f
168 Risk Score

Malware Insights

Formbook · confidence 95%

MITRE ATT&CK
T1204.002 Malicious File T1566.001 Spearphishing Attachment

The critical ClamAV detection and high-severity heuristics for OLE Equation Editor exploitation (CVE-2018-0798) strongly indicate this file is a malicious downloader. The embedded OLE object, specifically the Equation Editor component, is a known vector for delivering malware. The ClamAV signature 'Doc.Downloader.Formbook-bc97c1e0c33c3c93-9951465-0' directly attributes the file to the Formbook family, which is known for its downloader capabilities.

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
ae4ee92901b8027f38b477da20aa226fd97bd86610c06a0f9c4bb3f62e2227be		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/oleObject1.bin 4096 bytes
ooxml_oleobject_00_ole10native_00.bin
aab31fa49ea43bf74243db76adf3ccf3c9f294d3c68b57f7b7e9b1bda0f73946		 ole-package OOXML xl/embeddings/oleObject1.bin Ole10Native stream: oLe10nAtIVE 1650 bytes
emf_00.emf
868ab4bad566347dcc969d91e59ebb65eed584f6a8fcfb449014e39881a51e67		 ooxml-emf OOXML EMF part: xl/media/image7.emf 1099960 bytes

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