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

Static analysis result for SHA-256 b638e84ebb8dc98c…

MALICIOUS

Office (OLE) / .XLSX

379.5 KB First seen: 2022-06-09
MD5: a939343618a919163c47b7e03434bd24 SHA-1: 9ecaab8a842f4f8d85cfe25e1122f7796722755a SHA-256: b638e84ebb8dc98cc2b74b1ad6ece3175097a33cdeac2e1719cc011ce11a9f1e
220 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious Link T1566 Phishing 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 malformed and exhibits anomalies consistent with CVE-2018-0798, suggesting it's designed to exploit this vulnerability for initial execution. The document is also encrypted with a default password, further indicating it's a carrier for malicious code.

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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