Formbook — Office (OOXML) / .XLSX malware analysis

Static analysis result for SHA-256 e229a00da6f5a060…

MALICIOUS

Office (OOXML) / .XLSX

179.9 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 12.0000 First seen: 2022-03-03
MD5: feff5af028a4ae4b803c78b5d689606c SHA-1: c3c81e46f5525d7ff3c7663febcb3070de7cfa97 SHA-256: e229a00da6f5a060901cd6a46c810039d9e5bda1c78b29e81d04f138d1ebfa8b
168 Risk Score

Malware Insights

Formbook · confidence 95%

MITRE ATT&CK
T1204.002 Malicious File

The critical ClamAV detection identifies this file as Doc.Downloader.Formbook-bc97c1e0c33c3c93-9951465-0, a known Formbook variant. High-severity heuristics indicate the presence of an Equation Editor OLE object, specifically triggering CVE-2018-0798, which is commonly used to deliver Formbook. The embedded OLE object likely contains the exploit code to download and execute the secondary payload.

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
177f933b79dbd907846801ddb31cfc1cb5c8de420b6743fa81b0560e413320f5		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/oleObject1.bin 3584 bytes
ooxml_oleobject_00_ole10native_00.bin
4ef5e809279cfe396ddf23a86dac459bdf2f94997dee4a1ac6002b26d432b466		 ole-package OOXML xl/embeddings/oleObject1.bin Ole10Native stream: Ole10naTiVe 1248 bytes
emf_00.emf
bc1a75f99b79c98350da4bb5561eac01186dacf8d64f3ae8d4822e1a028644d9		 ooxml-emf OOXML EMF part: xl/media/image7.emf 1099960 bytes

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