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

Static analysis result for SHA-256 cef785e106912469…

MALICIOUS

Office (OLE) / .XLSX

1.20 MB
MD5: 571394f284fe4cf1829bfabf0e5534b8 SHA-1: 5bb6279a199f3c4ad7e41c6744601f43ecc021fb SHA-256: cef785e106912469a1ed039d6393877f6156ed15feb4019b15eb46def56b29a0
140 Risk Score

Malware Insights

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

The sample is an encrypted OOXML file that utilizes a default password, a common technique for obfuscation. It contains an embedded Equation Editor OLE object, which is frequently used to deliver exploits. The anomaly in the Ole10Native stream within the Equation Editor object suggests it carries a malicious 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.