Xls.Downloader.94c25b356b5a6cac-9978798-0 — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 6988a0aa635c18ec…

MALICIOUS

Office (OLE) / .XLSX

181.6 KB First seen: 2022-07-26
MD5: 29e34f6ac4428d885814569fde955321 SHA-1: acb427f920b588403c088dee736ec4084c9cd948 SHA-256: 6988a0aa635c18ecdcba1e5d5adf79d97b7724ee531bdb3497d7fa7294a7455b
262 Risk Score

Malware Insights

Xls.Downloader.94c25b356b5a6cac-9978798-0 · confidence 95%

MITRE ATT&CK
T1203 Exploitation for Client Execution T1059.007 JavaScript T1566.001 Spearphishing Attachment

The file is a password-encrypted OOXML document identified by ClamAV as Xls.Downloader.94c25b356b5a6cac-9978798-0. It contains an embedded OLE object that exploits CVE-2017-0199, acting as a remote loader. This exploit is designed to download and execute a secondary payload from the URL https://htmlpreview.github.io@url.welimitless.in/lLJZI. The document's encrypted nature and the embedded exploit carrier suggest it was likely delivered as a spearphishing attachment.

Heuristics 7

  • 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.
  • ClamAV: Xls.Downloader.94c25b356b5a6cac-9978798-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.94c25b356b5a6cac-9978798-0
  • 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://htmlpreview.github.io@url.welimitless.in/lLJZI