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

Static analysis result for SHA-256 abfb1cbb86c2cc20…

MALICIOUS

Office (OLE) / .XLSX

74.0 KB First seen: 2022-04-20
MD5: 20b9b35e357534544c05fa3c364bfdce SHA-1: dbe6891f796e7fcb8eefb0d154c64782da4543d4 SHA-256: abfb1cbb86c2cc20e82c1936cf328065e81cdd65a879d4518341869ed44be209
220 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious Link T1566 Phishing T1204.002 Malicious File

The sample is an encrypted Office document, identified as an exploit carrier due to its use of an Equation Editor OLE object. The presence of anomalous Equation Editor native stream data and CFB FAT corruption strongly suggests exploitation of CVE-2018-0798. The encryption and malformed structure are indicative of a malicious payload delivery mechanism, likely designed to bypass initial security checks.

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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