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

Static analysis result for SHA-256 624ef39c329f32ff…

MALICIOUS

Office (OLE) / .XLSX

255.5 KB First seen: 2022-06-14
MD5: 49aef9f8c433a74de599dfba11bc7f37 SHA-1: ef9ade7cbaf02836750a0956591963dc95f5a8d4 SHA-256: 624ef39c329f32ff84d85c14a24469fb745d379d5fb028e5a4cfc43a9f796c2b
180 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The sample is a password-encrypted Excel file that contains an embedded OLE object, identified as an Equation Editor object. This strongly suggests it's designed to exploit a known vulnerability within Equation Editor to execute arbitrary code. The encryption and malformed structure are common techniques to evade static analysis and deliver a malicious payload.

Heuristics 5

  • 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.
  • 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.