[ISN] File Sharing Vulnerability Discovered in Mac OS X

From: InfoSec News (isn@private)
Date: Mon Mar 01 2004 - 03:04:33 PST

  • Next message: InfoSec News: "[ISN] Youth cleared of trying to hack Mossad Web site"

    http://www.eweek.com/article2/0,1759,1540557,00.asp
    
    By Daniel Drew Turner 
    February 27, 2004   
     
    A security issue that could result in stolen passwords and data on
    Friday was revealed for Apple Computer Inc.'s Apple Filing Protocol, a
    component of Mac OS X 10.3.2, a k a Panther. The file protocol allows
    Macintosh users to access files on remote systems.
    
    An alert on the vulnerability was posted to the Security Focus BUGTRAQ
    Alert Service.
    
    In Mac OS X 10.2, Apple updated Apple Filing Protocol (AFP) to permit
    secure connections over SSH (Secure Shell) protocol. However, Chris
    Adams, a system administrator in San Diego, Calif., noted that while
    users could request secure connections, the system will not issue any
    alert or indication if an SSH connection is unavailable and then
    defaults to a non-secure connection. He noted that the only indication
    was a negative one - users must be aware that an alert "Opening Secure
    Connection" did not appear.
    
    According to Adams, this could result in users sending unencrypted
    passwords over an insecure connection.
    
    "Login credentials may be sent in cleartext or protected with one of
    several different hashed exchanges or Kerberos. There does not appear
    to have been any serious third-party security review of Apple's client
    or server implementations," Adams wrote in his report on the
    vulnerability.
    
    Speaking with eWEEK.com, Adams said that any such activity would only
    come as the result of an active attack. "OS X does warn you before
    using unencrypted passwords and AFP does prevent passive password
    collection by encrypting the log-in process to protect the password on
    its way to the server. This problem allows you to trick it into
    sending the unencrypted password to you instead of the intended
    server," he said.
    
    Adams pointed out that this sort of problem was not unique to Mac OS X.
    
    "As with Microsoft's Windows file sharing, AFP was designed for
    trusted LANs and some of the basic assumptions change when these
    systems are placed on the public Internet. Users on a secured LAN face
    relatively little risk; the most exposed are those using AFP over the
    Internet without a VPN," he said.
    
    Users of AFP on a secure network, Adams said, should have little to
    worry about.
    
    Adams said, systems open to remote connections, such as in educational
    institutions, would be vulnerable to "man in the middle" attacks,
    where a third server could intercept and harvest passwords
    surreptitiously.
    
    Compounding the problem, Adams added, was that SSH connectivity for
    AFP would not work at all in the initial releases of Mac OS X 10.3 and
    10.3.1.
    
    Adams observed that the problem arises from the fact that AFP treats
    SSH as an option rather than a user requirement.
    
    Though his BUGTRAQ warning provided workarounds, such as manually
    configuring a SSH tunnel or using SFTP instead, Adams suggested that
    SSH should be enabled by default for both client and server and the
    user interface modified to clearly warn when the system is unable to
    establish an SSH tunnel.
    
    SSH incorporates a number of extensively analyzed security
    precautions. Adams said that this is merely a matter of including
    those in the AFP user interface.
    
    Though Adams said he first reported this bug to Apple in early
    December 2003 and followed up weeks later, he received no response
    from the computer manufacturer.
    
    However, he told eWEEK.com that a final notice that he was going to
    release the information publicly resulted in a response on Friday.
    
    "It was what I was hoping for originally," he said, a notice that
    Apple was looking into the issue and was offering to coordinate
    efforts.
    
    An Apple representative declined to expand on Adam's statement.
    
    
    
    -
    ISN is currently hosted by Attrition.org
    
    To unsubscribe email majordomo@private with 'unsubscribe isn'
    in the BODY of the mail.
    



    This archive was generated by hypermail 2b30 : Mon Mar 01 2004 - 05:30:50 PST