Exploit:W32/WormLink

Classification

Malware

Exploit

W32

Exploit:W32/WormLink.[variant], Exploit:Win32/CplLnk.A (Microsoft)

Summary

Exploit:W32/WormLink is a generic detection for malicious shortcut (.LNK) files embedded in a document file that can exploit the CVE-2010-2568 vulnerability in various versions of Windows.

Security programs use generic detections that look for broad patterns of code or behavior to identify similar programs or files. If you suspect the file was incorrectly detected, go to: Removal: Suspect a file is incorrectly detected (a False Positive)?.

Automatic action

Based on the settings of your F-Secure security product, it will either move the file to the quarantine where it cannot spread or cause harm, or remove it.

Exploit prevention

The vulnerabilities leveraged by the exploits are usually application or platform specific; in other words, a specific program (or even a specific version of a particular program) must be installed on the machine in order for the exploit to be effective.

To prevent exploitation of such vulnerabilities, please refer to the application vendor for the latest updates and additional advice.

Suspect a file is incorrectly detected (a False Positive)?

A False Positive is when a file is incorrectly detected as harmful, usually because its code or behavior resembles known harmful programs. A False Positive will usually be fixed in a subsequent database update without any action needed on your part. If you wish, you may also:

  • Check for the latest database updates

    First check if your F-Secure security program is using the latest detection database updates, then try scanning the file again.

  • Submit a sample

    After checking, if you still believe the file is incorrectly detected, you can submit a sample of it for re-analysis.

    NOTE If the file was moved to quarantine, you need to collect the file from quarantine before you can submit it.

  • Exclude a file from further scanning

    If you are certain that the file is safe and want to continue using it, you can exclude it from further scanning by the F-Secure security product.

    Note You need administrative rights to change the settings.

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Submit a sample

Submit a file or URL for further analysis.

Technical Details

Exploit:W32/WormLink identifies malicious shortcut LNK files designed to exploit the known CVE-2010-2568 vulnerability in the Windows Shell program of various versions of Microsoft Windows (XP SP3, Server 2003 SP2, Vista SP1 and SP2, Server 2008 SP2 and R2, and Windows 7).

The CVE-2010-2568 vulnerability was most notable for being the flaw used by the stealth threat Stuxnet to gain access to target systems, though it has also since been leveraged by other malware families.

Exploit:W32/WormLink was first seen in 2010 spreading via infected removable drives. In this scenario, simply browsing to the removable media drive using an application that displays shortcut icons (like Windows Explorer) will cause the system to automatically execute the malware as soon as the LNK file is read.

The malicious LNK files may also be distributed embedded in document files that support embedded shortcuts. The most common type of document file with this functionality is Microsoft Word files, though other document types are possible. The bait documents are typically distributed as attachments to email messages. If the user opens the attached document and the operating system attempts to resolve the shortcut file's icon, the vulnerability is triggered and associate malicious payload (which is contained in a separate component or file) is executed. The user does not need to click on the shortcut icon itself for the exploit to run.

For more information about the CVE-2010-2568 vulnerability, see: