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

Static analysis result for SHA-256 94fd32fdbc89d840…

MALICIOUS

Office (OLE) / .XLSX

229.0 KB
MD5: a4fc3513e165f8c4a18fc42f60698fda SHA-1: 0bad1dd33712c088697bc2d4f58746d6409744cf SHA-256: 94fd32fdbc89d8401d37aaedb27747c710f2733da14b8df9396ae55f8db0bdad
220 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1027 Obfuscated Files or Information T1566.001 Phishing: Spearphishing Attachment T1027.002 Software Packing

The sample is an encrypted Office document containing an embedded OLE object (xl/embeddings/oleObject1.bin) that targets CVE-2018-0798. The use of a default password for encryption (VelvetSweatshop) and CFB FAT corruption indicates an attempt to evade detection by security software. The high entropy of the native stream in the embedded object suggests the presence of shellcode for the same exploit.

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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