Alibaba Alipay Remote Code Execute Vulnerability

by cocoruder(frankruder_at_hotmail.com)
http://ruder.cdut.net


Summary:

    Alipay is China’s leading online payment service, and a division of 
Alibaba.com. It enables individuals and businesses to securely, easily and 
quickly send and receive payments online. Alipay works like an escrow 
service, solving the issue of settlement risk in China. More details:

    https://www.alipay.com

    There exists a remote code execute vulnerability in alipay's passsword 
input control "pta.dll". A remote attacker who successfully exploit these 
vulnerabilities can completely take control of the affected system.



Affected Software Versions:

    All current versions



Details:
	
    This vulnerability exist in the function "Remove()" educed by 
"pta.dll", following are some related imformations:

    InprocServer32:	pta.dll
    ClassID	  : 	66F50F46-70A0-4A05-BD5E-FBCC0F9641EC

    [id(0x60030001), helpstring("method Remove")]
    void Remove([in] int idx);

    Let's see How function "Remove()" process the parameter "idx"：

	.text:10003D4E ; Remove
	.text:10003D4E
	.text:10003D4E sub_10003D4E    proc near			; DATA XREF: .rdata:1000B3A4o
	.text:10003D4E							; .rdata:1000B41Co ...
	.text:10003D4E
	.text:10003D4E arg_0           = dword ptr  4
	.text:10003D4E arg_4           = dword ptr  8
	.text:10003D4E
	.text:10003D4E                 mov     eax, [esp+arg_4]		
	.text:10003D52                 test    eax, eax
	.text:10003D54                 jl      short loc_10003D78	
	.text:10003D56                 push    esi
	.text:10003D57                 mov     esi, [esp+4+arg_0]	; get idx
	.text:10003D5B                 shl     eax, 4			; idx << 4
	.text:10003D5E                 add     eax, [esi+8]		; [esi+8]=0
	.text:10003D61                 push    edi			;
	.text:10003D62                 mov     edi, eax			; idx << 4 ==>edi
	.text:10003D64                 mov     eax, [edi+8]		; [(idx << 4)+8] 
==>eax
	.text:10003D67                 push    eax
	.text:10003D68                 mov     ecx, [eax]		; [[(idx << 
4)+8]]==>ecx
	.text:10003D6A                 call    dword ptr [ecx+8]	; [[[(idx << 
4)+8]]+8]==>jmp addr
	.text:10003D6D                 push    edi
	.text:10003D6E                 lea     ecx, [esi+4]
	.text:10003D71                 call    sub_10003F35
	.text:10003D76                 pop     edi
	.text:10003D77                 pop     esi
	.text:10003D78
	.text:10003D78 loc_10003D78:					; CODE XREF: sub_10003D4E+6j
	.text:10003D78                 xor     eax, eax
	.text:10003D7A                 retn    8
	.text:10003D7A sub_10003D4E    endp

    The idx is a DWORD vaule what we can control, so we can complete an 
interesting attack, for example when we set the idx 0x41414141, the 
procedure will execute codes of address [[[14141410h+8]]+8].



Solution:

    Set a killbit for "pta.dll", or, delete %system%\aliedit\pta.dll if you 
do not use Alipay.



Disclosure Timeline:

    2007.02.07		Advisory release



Attached File:

    Here give an exploit, we se all address 0x0d0d0d0d which will access 
its value, can gain attack result nicely.
    Warning: This exploit is just used for reproducing the vulnerability, 
please do not used for others.

    http://ruder.cdut.net/attach/exploit_alipay_vul.rar



--EOF--

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