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

Static analysis result for SHA-256 b81ab749a594612a…

MALICIOUS

Office (OLE) / .XLSX

1.23 MB
MD5: b2ddcb7e038eda725b9bdae5b5b97dfc SHA-1: 8875b3c7dbf066d4fad93c79f212aa12acaedf82 SHA-256: b81ab749a594612a4d18813627b1f08aafa332e09521bd143461052614b6262b
140 Risk Score

Malware Insights

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

The sample is an OOXML file encrypted with a default password, indicating an attempt to hide its malicious contents. It contains an embedded Equation Editor OLE object, a common technique for delivering exploits. The anomaly in the Ole10Native stream suggests the Equation Editor object is being used to carry a payload, likely an exploit targeting a vulnerability within the Equation Editor itself.

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.