Formbook — Office (OOXML) / .XLSX malware analysis

Static analysis result for SHA-256 42981776a53c0b27…

MALICIOUS

Office (OOXML) / .XLSX

179.7 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 12.0000 First seen: 2022-03-01
MD5: be819e6066417b928b2e8c5b60e210ba SHA-1: 20de44614e48f114a5880af86f0215c1ebb80a03 SHA-256: 42981776a53c0b27a6fd4b0922c9d458bce23c81b382406dc8bfee53ccd9ed79
168 Risk Score

Malware Insights

Formbook · confidence 95%

MITRE ATT&CK
T1204.002 Malicious File

The file is detected as a Formbook downloader by ClamAV, exploiting CVE-2018-0798 via an embedded Equation Editor OLE object. This technique is commonly used to download and execute a secondary payload. The presence of a hidden sheet further supports the malicious intent by concealing malicious content.

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
9b31fe97cacf1882621e8aa22ee3d58ff5739c3be1278a1fc9323f3e659574b7		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/oleObject1.bin 4096 bytes
ooxml_oleobject_00_ole10native_00.bin
6851bd25339a48488bed804b72bdf71dbe654833ccbfa18750df5e4e97a80d1d		 ole-package OOXML xl/embeddings/oleObject1.bin Ole10Native stream: ole10NAtIvE 1679 bytes
emf_00.emf
bc1a75f99b79c98350da4bb5561eac01186dacf8d64f3ae8d4822e1a028644d9		 ooxml-emf OOXML EMF part: xl/media/image7.emf 1099960 bytes

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