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

Static analysis result for SHA-256 c4ea61fbcb7d6d02…

MALICIOUS

Office (OLE) / .XLSX

1.17 MB
MD5: 3b512ebe6403a75297f37f73eb3fd81b SHA-1: 6ab23d06b933f9e312e926bc5601690538fdd1c4 SHA-256: c4ea61fbcb7d6d02280ac5ff9d41fe65ab42caeaededfe21d46caccca3d69611
140 Risk Score

Malware Insights

MITRE ATT&CK
T1204.002 User Execution: Malicious File T1059 Command and Scripting Interpreter T1203 Exploitation for Client Execution

The sample is an encrypted OOXML file that uses the 'VelvetSweatshop' default password to bypass static analysis. It contains an embedded OLE object with the Equation Editor CLSID and a malformed Ole10Native stream, which is a classic signature of Equation Editor exploits (CVE-2017-11882). No scripts were extracted from this sample, but the exploit payload is contained within the embedded OLE object.

Heuristics 4

  • 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.
  • 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.
  • Equation Editor object carries payload-like Ole10Native stream high OLE_EQUATION_OLE10NATIVE_PAYLOAD_ANOMALY
    Default-encrypted OOXML embedded OLE object declares the Equation Editor CLSID but stores a large high-entropy Ole10Native stream with malformed package sizing. This is exploit-shaped Equation/OLE payload evidence.
  • 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.