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

Static analysis result for SHA-256 c7b835bd3e5e7c83…

MALICIOUS

Office (OLE) / .XLSX

77.2 KB First seen: 2022-06-01
MD5: 78e17220ee3156b781b82c1d2009f45a SHA-1: 0a289b06aa1ce9ed49cf1e3bbddce50b1c3de710 SHA-256: c7b835bd3e5e7c8305d215125c8e5b0887d35b45ba2b6eb940bebcf3e069f032
220 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious Link T1566 Phishing T1059 Command and Scripting Interpreter

The sample is an encrypted Office document containing an Equation Editor OLE object, which is a known carrier for exploits like CVE-2018-0798. The presence of anomalous Equation Editor native stream data and CFB FAT corruption strongly indicates it's designed to exploit this vulnerability for initial execution. The encrypted nature and the specific exploit carrier point towards a malicious payload delivery mechanism.

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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