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

Static analysis result for SHA-256 badf745445821970…

MALICIOUS

Office (OLE) / .XLSX

379.7 KB First seen: 2022-06-09
MD5: 5f093907241495442ba42d694c0e9c5d SHA-1: c1178a99d79ad875a6d90e34f0013b4d52d792a3 SHA-256: badf745445821970547fb29f4d50423e38d4df99761b731ecbb5138bd3f55d98
220 Risk Score

Malware Insights

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

The sample is an encrypted Office XLSX file. Static analysis identified an embedded Equation Editor OLE object within the 'xl/embeddings/oleObject1.bin' stream. This object exhibits characteristics indicative of the CVE-2018-0798 vulnerability, specifically an anomalous Equation Editor native stream with an invalid MTEF version and high entropy. The document is also flagged as an exploit carrier and contains CFB FAT corruption, suggesting it is designed to deliver a secondary malicious 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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