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

Static analysis result for SHA-256 591112f24436a945…

MALICIOUS

Office (OLE) / .XLSX

1.29 MB
MD5: d1d0f5f4b3ba140103e5a5ccc66c5afb SHA-1: 0efea53d37f80011b735472fea4d2d1b88af935a SHA-256: 591112f24436a94505c4b01d4c57b88b8cea012538af41a0cb2179a4b2d3da37
140 Risk Score

Malware Insights

MITRE ATT&CK
T1566.002 Spearphishing Attachment T1204.002 Malicious File

The sample is an OOXML file that is encrypted with a default password and contains an embedded Equation Editor OLE object. This object carries a payload-like Ole10Native stream, indicating it is likely used to exploit a vulnerability, such as CVE-2017-11882, to execute arbitrary code. No specific family could be identified, but the delivery mechanism is consistent with a targeted attack.

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.