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

Static analysis result for SHA-256 ecff5731657af3fa…

MALICIOUS

Office (OLE) / .XLSX

20.7 KB First seen: 2022-07-29
MD5: 1e77d655c90902f35e687c6e7e2fa68a SHA-1: 9d5278e2d29cb962ee6b6b80a0d128bb9a0e180d SHA-256: ecff5731657af3faef9d2f1b331d026da757a97f00b49f686c38e6f7a8957909
202 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious Link T1204.001 Malicious Link: Embedded Link T1059 Command and Scripting Interpreter T1059.001 Command and Scripting Interpreter: PowerShell T1566 Phishing T1566.001 Phishing: Spearphishing Attachment T1566.002 Phishing: Spearphishing Link

The sample is a password-encrypted Office document that exploits CVE-2017-0199. This vulnerability allows it to act as a remote loader, fetching and executing a payload from the embedded URL 'https://myown.bio/NLC'. The encryption and malformed structure indicate an attempt to evade detection.

Heuristics 6

  • OLE2Link / URL Moniker → remote loader — CVE-2017-0199 critical CVE likely CVE_2017_0199
    Document contains an embedded OLE link object whose URL Moniker points to a remote URL. When the host file is opened, Office follows the link, downloads the URL, and processes the response based on its Content-Type (HTA -> mshta.exe, RTF → Word, etc.) — the documented CVE-2017-0199 primitive. The URL extension is not a reliable filter; servers can return different payloads to Office's user agent.
  • Encrypted Office package with CFB FAT corruption critical OLE_ENCRYPTED_AND_MALFORMED
    Encrypted-package shape co-occurs with FAT-chain corruption — the documented combined evasion form.
  • 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.
  • Office document is password-encrypted medium OFFICE_ENCRYPTED_PACKAGE
    OLE container holds MS-OFFCRYPTO encrypted package (Standard Encryption (Office 2007, AES)).
  • 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.
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL https://myown.bio/NLC

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