Formbook — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 e3aa1a9e723f5373…

MALICIOUS

Office (OLE) / .XLSX

190.9 KB
MD5: a14f67162e13e362a1820027deed20dd SHA-1: ba9ba507c0e17248fac796f1876fc5c0290a00f2 SHA-256: e3aa1a9e723f537320709a71f54682264e6659a106fe4c39749436d0bf5b6f52
280 Risk Score

Malware Insights

Formbook · confidence 95%

MITRE ATT&CK
T1204 Malicious Link T1566.001 Spearphishing Attachment T1203 Exploitation for Client Execution

The sample is a password-encrypted Office document identified as a downloader for the Formbook family. It contains an Equation Editor OLE object that exploits CVE-2018-0798, indicated by the 'OLE_EQUATION_EDITOR' and 'CVE_2018_0798_EQUATION_NATIVE_ANOMALY' heuristics. The encryption and malformed structure ('OLE_ENCRYPTED_AND_MALFORMED') are common techniques for obfuscating malicious content. The ClamAV detection further confirms its malicious nature as a Formbook downloader.

Heuristics 7

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Default-encrypted OOXML 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
    Default-encrypted OOXML contains embedded Equation Editor data with anomalous native stream bytes consistent with a CVE-2018-0798-style exploit. This is treated as likely CVE evidence because the Equation object is malformed and payload-like.
  • Encrypted Office package with CFB FAT corruption critical OLE_ENCRYPTED_AND_MALFORMED
    Encrypted-package shape co-occurs with FAT-chain corruption — the documented combined evasion form.
  • ClamAV: Doc.Downloader.Formbook-bc97c1e0c33c3c93-9951465-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.Formbook-bc97c1e0c33c3c93-9951465-0
  • Default-encrypted OOXML exploit carrier layout high OOXML_ENCRYPTED_EXPLOIT_CARRIER_SHAPE
    Default-password encrypted OOXML package contains embedded OLE object parts and additional activation/decoy parts. This layout is common in malicious Excel exploit delivery and requires inspecting the decrypted package.
  • Office document is password-encrypted medium OFFICE_ENCRYPTED_PACKAGE
    OLE container holds MS-OFFCRYPTO encrypted package (Standard Encryption (Office 2007, AES)).
  • Office OOXML encrypted with default VelvetSweatshop password medium OFFICE_DEFAULT_PASSWORD_ENCRYPTED_OOXML
    OLE EncryptedPackage decrypts with Excel's built-in VelvetSweatshop password. Office opens this transparently, and malware uses it to hide OOXML exploit parts from scanners that only inspect the outer OLE container.

Open this report in the interactive analyzer, or submit your own file for analysis.