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

Static analysis result for SHA-256 c437bba4da7329b0…

MALICIOUS

Office (OLE) / .XLSX

1.22 MB
MD5: a48dabced116551bd79cc2b696d7f8f6 SHA-1: 3e977573e9faf898220fa125f4dd18432107d219 SHA-256: c437bba4da7329b098e05365b1c6a0e1379ba457d2eff042104b9a79e2ba0294
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 obfuscating malicious content. It contains an embedded Equation Editor OLE object, which is frequently used to deliver exploits. The presence of an anomalous Ole10Native stream within the Equation Editor object suggests it carries 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.