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

Static analysis result for SHA-256 98a159509743160e…

MALICIOUS

Office (OLE) / .XLSX

1.18 MB
MD5: ca222ef1f388ba2ba14776487c4a8a30 SHA-1: dec6d20f75aa536b1b8ba6de28968db15793e806 SHA-256: 98a159509743160e7068573802f990015bf787dafbb0462b200ee5b5047f42dd
140 Risk Score

Malware Insights

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

The sample is an encrypted OOXML file that utilizes a default password, a common technique for obfuscating malicious content. It contains embedded OLE objects, specifically identified as Equation Editor objects, which are frequently used to deliver exploits. The presence of an 'Ole10Native' stream within the Equation Editor object, with an anomalous header and a size mismatch, strongly suggests it carries a secondary payload. The file's structure and the nature of the embedded objects point towards an exploit delivery mechanism.

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.