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

Static analysis result for SHA-256 52ec148b20e761dc…

MALICIOUS

Office (OLE) / .XLSX

2.19 MB
MD5: bb5249cfa26587bfa43c93330962141a SHA-1: ff0c817f5d5f0936131aae8b134d33ce511c9c8c SHA-256: 52ec148b20e761dc465596db87e9119d44acd906ace191de880ec8a2ae001be7
180 Risk Score

Malware Insights

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

The sample is an encrypted OOXML file that contains an embedded Equation Editor OLE object. Heuristics indicate this object is anomalous and carries a high-entropy payload, strongly suggesting it's an exploit carrier. Specifically, the 'CVE_2018_0798_EQUATION_NATIVE_ANOMALY' and 'OLE_EQUATION_OLE10NATIVE_PAYLOAD_ANOMALY' firings point to the exploitation of CVE-2018-0798 via the Equation Editor. The default password encryption further supports its nature as a malicious document.

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.
  • 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.
  • 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.