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

Static analysis result for SHA-256 2891d80da7d30565…

MALICIOUS

Office (OLE) / .XLSX

255.8 KB First seen: 2022-06-14
MD5: 33fc3bc8836e88d5bbf871036bacb2e9 SHA-1: 958c0a6bfa40fa4dd85a431a3ca3529b6253b342 SHA-256: 2891d80da7d30565721857027cf36fe12307fcb714ad7cccdd500ffb2269b27c
220 Risk Score

Malware Insights

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

The sample is an encrypted Office document that contains an embedded Equation Editor OLE object. Heuristics indicate this object is anomalous and specifically flags CVE-2018-0798, suggesting exploitation of this vulnerability. The encryption and malformed nature of the OLE package further support its role as an exploit carrier. The likely intent is to leverage the Equation Editor vulnerability to execute 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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