Malicious Office (OLE) / .XLSX — malware analysis report

Static analysis result for SHA-256 26a87d2070b101e8…

MALICIOUS

Office (OLE) / .XLSX

255.5 KB First seen: 2022-06-14
MD5: 87b4ddc64c88f00cafe8f404f92b27c2 SHA-1: 2b8b95e28a2243ded0934468758fedddfb1c428a SHA-256: 26a87d2070b101e8cd1781a19dd8ff3d0c339bcf9b61c9d055bc221fc9ac9d96
220 Risk Score

Malware Insights

MITRE ATT&CK
T1204.002 Malicious File T1559.001 Component Object Model Hijacking

The sample is an encrypted Office document that contains an embedded Equation Editor OLE object. Heuristics indicate this object is anomalous and exploits CVE-2018-0798, a vulnerability in the Equation Editor. The document is also flagged as an exploit carrier, suggesting it's designed to deliver a secondary payload.

Heuristics 6

  • 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.
  • 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.

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