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

Static analysis result for SHA-256 4677020f17b9de0f…

MALICIOUS

Office (OLE) / .XLSX

379.3 KB First seen: 2022-06-08
MD5: ae4ff895012e1f6266adbd976d74ff57 SHA-1: fb4da19d70cce4f65541b57181a61c337f3659a5 SHA-256: 4677020f17b9de0f4df993ca999235f0f738ff98b24e7aa2ca46bd83d6535787
220 Risk Score

Malware Insights

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

The sample is an encrypted Office XLSX file. Static analysis identified an Equation Editor OLE object within the 'xl/embeddings/oleObject1.bin' stream, which is a known carrier for exploits. The heuristics indicate a high likelihood of exploitation targeting CVE-2018-0798 due to anomalous Equation Editor native stream properties. The encryption and malformed structure further suggest malicious intent, likely to deliver a second-stage 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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