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

Static analysis result for SHA-256 bf1fa14c2ccaed57…

MALICIOUS

Office (OLE) / .XLSX

1.26 MB
MD5: 794c22eb8c00fb93fbd3c14c5208e2e2 SHA-1: ce6232072a8080fe1707671a76d12543123b3748 SHA-256: bf1fa14c2ccaed571bac90e4e558904a71b35e6a295799a87078044f7e46ea01
140 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.001 User Execution: Malicious Link

The sample is an encrypted OOXML file that utilizes a default password, a common technique for obfuscating malicious content. It contains an Equation Editor OLE object, which is frequently used to deliver exploits. The presence of an 'Ole10Native' stream within the Equation Editor object, with an anomalous header and a declared inner size far exceeding the stream size, strongly suggests it's designed to carry a secondary payload. No scripts were extracted, and no document body was available for analysis.

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.