Formbook — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 415ae4aad2ffa59d…

MALICIOUS

Office (OLE) / .XLSX

224.2 KB First seen: 2022-04-25
MD5: 002426ee63b2cd0fad6315ad30451111 SHA-1: 9d20a9cd89c025c6daffe4b112617f74f35062d4 SHA-256: 415ae4aad2ffa59d3fa9c1d320ae286fcd885f2289923940d3a6b3ddc17fdbb3
280 Risk Score

Malware Insights

Formbook · confidence 95%

MITRE ATT&CK
T1204 Malicious Link T1566 Phishing T1059.003 Windows Command Shell

The file is an encrypted Office document that exhibits characteristics of an exploit carrier, specifically related to the Equation Editor OLE object. The presence of heuristics like OLE_EQUATION_EDITOR and CVE_2018_0798_EQUATION_NATIVE_ANOMALY strongly suggests an attempt to leverage vulnerabilities within this component. ClamAV detection as 'Doc.Downloader.Formbook-bc97c1e0c33c3c93-9951465-0' indicates that this file is a downloader for the Formbook malware family. The encryption and malformed structure further point to a malicious intent to evade static analysis and deliver a secondary payload.

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.