[LeapFTP] "PASV" Reply Buffer Overflow Vulnerability
From: :: Operash :: (nesumin_at_SOFTHOME.NET)
Date: Mon, 9 Jun 2003 12:19:44 +0900 To: NTBUGTRAQ@LISTSERV.NTBUGTRAQ.COM
SUMMARY : [LeapFTP] "PASV" Reply Buffer Overflow Vulnerability
PRODUCT : LeapFTP
VERSIONS : 18.104.22.1680
VENDOR : LeapWare (http://www.leapware.com/)
SEVERITY : Critical.
DISCOVERED BY : nesumin
AUTHOR : :: Operash ::
REPORTED DATE : 2003-05-07
RELEASED DATE : 2003-06-09
LeapFTP is a GUI base FTP Client for Windows.
The buffer overflow occurs on the stack area if the reply that contains
a long string is returned from a server for the "PASV" command request.
By exploiting this vulnerability, an attacker can execute an arbitrary
code on the user's system if the user connects to the malicious server.
With this vulnerability, there could be following risks;
* Infection with Virus or Trojan, etc.
* Destruction of the system.
* Leak or alteration of the local data.
2. SYSTEMS AFFECTED
And previous versions may have same vulnerability.
3. SYSTEMS NOT AFFECTED
Tested versions :
Tested platforms :
Windows 98SE Japanese
Windows 2000 Professional SP3 Japanese
5. VENDOR STATUS
2003-05-21 Vendor released fixed-version (22.214.171.1242) and the security
Upgrade to version 126.96.36.1992 or later version.
7. TECHNICAL DETAILS
LeapFTP tries to create a connection of data transfer to get
the File List or etc when it connected to a FTP server.
Then, it requests the IP address and port number by using
"PASV" command if PASV-MODE is enabled.
It causes the buffer overflow on the stack area if the server's
reply for this "PASV" request has a long IP address like following.
<--- 227 (AAAAAAAAAA ..... (over 0x421 bytes) ..... ,1,1,1,1,1)
And this buffer overflow can overwrite a Structured Exception Handler
on the stack area with an arbitrary value by specifying the address
data over 0x421 bytes.
If a Structured Exception Handler is overwritten with the address of
buffer that has an arbitrary code or the address of instruction data
that redirects to there, the processing path moves to that buffer.
Therefore, it is able to execute an arbitrary code as the privilege of
8. SAMPLE CODE
9. TIME TABLE
2003-04-20 Discovered this vulnerability.
2003-05-07 Reported to vendor.
2003-05-08 Received a reply from vendor.
2003-05-14 Received a fixed-version from vendor.
2003-05-15 Conveyed to vendor that the fix has been done.
2003-05-21 Vendor released fixed-version.
2003-06-09 Released this advisory.
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11. CONTACT, ETC
:: Operash ::
imagine (Operash Webmaster)
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