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

Static analysis result for SHA-256 fcace88107dbbf56…

MALICIOUS

Office (OLE) / .XLSX

1.23 MB
MD5: 2cd62d578abb738b28857caff42e6be5 SHA-1: 71848b71afe4303b071eed52ae8c3d88d79126c4 SHA-256: fcace88107dbbf5647443eb1d73f123f2907513d1c3aaaee31b73404bebd4024
140 Risk Score

Malware Insights

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

The sample is an OOXML file that is encrypted with a default password and contains an Equation Editor OLE object. This object is known to be used as an exploit carrier, specifically for delivering malicious payloads via vulnerabilities in the Equation Editor component. The presence of an 'Ole10Native' stream within the Equation Editor object, with an anomalous header and a large declared inner size, strongly suggests it contains an embedded executable or script designed to be run.

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.