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

Static analysis result for SHA-256 c35e2e17c0663fa4…

MALICIOUS

Office (OLE) / .XLSX

1.21 MB
MD5: 91ea1fd23a564a74b71f143b86968143 SHA-1: 903922a4c4e7104dce009d9a01ddf062604e7f3e SHA-256: c35e2e17c0663fa4adc5a1b219f44cdf90e9ec8a68fe23bf65b43c0ba208dbcb
140 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File

The sample is an encrypted OOXML file that contains an embedded Equation Editor OLE object. This object exhibits anomalies suggesting it carries a payload, a common technique for exploiting vulnerabilities like CVE-2017-11882. The presence of the Equation Editor OLE object and the encrypted nature of the document strongly indicate an exploit carrier designed to deliver a secondary malicious payload.

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.