Description

The software attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.

Soft links are a UNIX term that is synonymous with simple shortcuts on windows based platforms.

Modes of Introduction:

– Implementation

Likelihood of Exploit: Medium

Related Weaknesses

CWE-706
CWE-706

Consequences

Confidentiality, Integrity, Access Control: Read Files or Directories, Modify Files or Directories, Bypass Protection Mechanism

An attacker may be able to traverse the file system to unintended locations and read or overwrite the contents of unexpected files. If the files are used for a security mechanism then an attacker may be able to bypass the mechanism.

Other: Execute Unauthorized Code or Commands

Windows simple shortcuts, sometimes referred to as soft links, can be exploited remotely since a “.LNK” file can be uploaded like a normal file. This can enable remote execution.

Potential Mitigations

Phase: Architecture and Design

Description: 

CVE References

• CVE-1999-1386
  • Some versions of Perl follows symbolic links when running with the -e option, which allows local users to overwrite arbitrary files via a symlink attack.

• CVE-2000-1178
  • Text editor follows symbolic links when creating a rescue copy during an abnormal exit, which allows local users to overwrite the files of other users.

• CVE-2004-0217
  • Antivirus update allows local users to create or append to arbitrary files via a symlink attack on a logfile.

• CVE-2003-0517
  • Symlink attack allows local users to overwrite files.

• CVE-2004-0689
  • Window manager does not properly handle when certain symbolic links point to “stale” locations, which could allow local users to create or truncate arbitrary files.

• CVE-2005-1879
  • Second-order symlink vulnerabilities

• CVE-2005-1880
  • Second-order symlink vulnerabilities

• CVE-2005-1916
  • Symlink in Python program

• CVE-2000-0972
  • Setuid product allows file reading by replacing a file being edited with a symlink to the targeted file, leaking the result in error messages when parsing fails.

• CVE-2005-0824
  • Signal causes a dump that follows symlinks.

• CVE-2001-1494
  • Hard link attack, file overwrite; interesting because program checks against soft links

• CVE-2002-0793
  • Hard link and possibly symbolic link following vulnerabilities in embedded operating system allow local users to overwrite arbitrary files.

• CVE-2003-0578
  • Server creates hard links and unlinks files as root, which allows local users to gain privileges by deleting and overwriting arbitrary files.

• CVE-1999-0783
  • Operating system allows local users to conduct a denial of service by creating a hard link from a device special file to a file on an NFS file system.

• CVE-2004-1603
  • Web hosting manager follows hard links, which allows local users to read or modify arbitrary files.

• CVE-2004-1901
  • Package listing system allows local users to overwrite arbitrary files via a hard link attack on the lockfiles.

• CVE-2005-1111
  • Hard link race condition

• CVE-2000-0342
  • Mail client allows remote attackers to bypass the user warning for executable attachments such as .exe, .com, and .bat by using a .lnk file that refers to the attachment, aka “Stealth Attachment.”

• CVE-2001-1042
  • FTP server allows remote attackers to read arbitrary files and directories by uploading a .lnk (link) file that points to the target file.

• CVE-2001-1043
  • FTP server allows remote attackers to read arbitrary files and directories by uploading a .lnk (link) file that points to the target file.

• CVE-2005-0587
  • Browser allows remote malicious web sites to overwrite arbitrary files by tricking the user into downloading a .LNK (link) file twice, which overwrites the file that was referenced in the first .LNK file.

• CVE-2001-1386
  • “.LNK.” – .LNK with trailing dot

• CVE-2003-1233
  • Rootkits can bypass file access restrictions to Windows kernel directories using NtCreateSymbolicLinkObject function to create symbolic link

• CVE-2002-0725
  • File system allows local attackers to hide file usage activities via a hard link to the target file, which causes the link to be recorded in the audit trail instead of the target file.

• CVE-2003-0844
  • Web server plugin allows local users to overwrite arbitrary files via a symlink attack on predictable temporary filenames.