Formbook — Office (OOXML) / .XLSX malware analysis

Static analysis result for SHA-256 a224de0a20a6099c…

MALICIOUS

Office (OOXML) / .XLSX

180.0 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 12.0000 First seen: 2022-03-18
MD5: 87a72639c8faf770f4f07315dad54d64 SHA-1: a9acefa3a5f6011a40509a87c645c0b6d085fe2e SHA-256: a224de0a20a6099cc5b59ced3c0a0fd69e34334b33cfa024e4fe9e968cd2443a
168 Risk Score

Malware Insights

Formbook · confidence 95%

MITRE ATT&CK
T1204 Malicious File Execution T1059 Command and Scripting Interpreter

The critical ClamAV detection and high-severity heuristics for OLE Equation Editor anomalies (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 for further malicious payloads. The presence of an embedded OLE object and a hidden worksheet further supports this analysis.

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
31cb50a715600871e9785c7e6fe52dbdd6ffc743d5a0e3a9e3c546594ba90a21		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/oleObject1.bin 3584 bytes
ooxml_oleobject_00_ole10native_00.bin
84dd317df91f6c7e411dc3ddb80a4994ac90e4786c8bf4b2fb07ebffd1a37594		 ole-package OOXML xl/embeddings/oleObject1.bin Ole10Native stream: OLE10NAtive 1376 bytes
emf_00.emf
bc1a75f99b79c98350da4bb5561eac01186dacf8d64f3ae8d4822e1a028644d9		 ooxml-emf OOXML EMF part: xl/media/image7.emf 1099960 bytes

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