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Category:   Application (Generic)  >   CA ARCserve Backup Vendors:   CA
CA BrightStor Backup Buffer Overflow in Mediasvr.exe Lets Remote Users Execute Arbitrary Code
SecurityTracker Alert ID:  1017830
SecurityTracker URL:
CVE Reference:   CVE-2007-1785   (Links to External Site)
Updated:  Apr 25 2007
Original Entry Date:  Mar 30 2007
Impact:   Execution of arbitrary code via network, User access via network
Fix Available:  Yes  Vendor Confirmed:  Yes  Exploit Included:  Yes  
Version(s): 11.5 SP3 and prior versions; Tested on (SP2) with latest patches
Description:   A vulnerability was reported in CA BrightStor Backup. A remote user can execute arbitrary code on the target system.

A remote user can send specially crafted RPC data to trigger a buffer overflow in 'Mediasvr.exe' and execute arbitrary code on the target system. The code will run with the privileges of the target service.

The vendor has been notified.

A demonstration exploit is available at:

The original advisory is available at:

Shirkdog reported this vulnerability.

Impact:   A remote user can execute arbitrary code on the target system.
Solution:   The vendor has issued the following patches.

BrightStor ARCserve Backup r11.5 SP3 - QO87569
BrightStor ARCserve Backup r11.5 SP2 - QO87570
BrightStor ARCserve Backup r11.1 - QO87573
BrightStor ARCserve Backup r11.0 - QI82917
BrightStor Enterprise Backup r10.5 - QO87575
BrightStor ARCserve Backup v9.01 - QO87574

The CA advisory is available at:

Vendor URL: (Links to External Site)
Cause:   Boundary error
Underlying OS:  Windows (Any)

Message History:   None.

 Source Message Contents

Subject:  [Full-disclosure] CA Brightstor Backup Mediasvr.exe Remote Code

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[Shirkdog Security Advisory SHK-004]

Computer Associates (CA) Brightstor Backup Mediasvr.exe Remote Code 

Description of Application:

Brightstor ARCserv Backup provides a complete, flexible and integrated 
backup and recovery solution for Windows, NetWare, Linux and UNIX 

There seems to be an design error in the handling of RPC data with xdr 
procedures across several .dll's imported by Mediasvr.exe. Four bytes from 
an RPC packet are processed as a particular address (xdr_handle_t data which 
is run through multiple bit shifts, and reversing of bytes), and eventually 
loaded into ECX. The 191 (0xbf) procedure, followed by nulls (at least 8 
bytes of nulls, which may be Null Credentials and Auth?) leads to an 
exploitable condition.

.text:0040AACD 008 mov ecx, [esp+8]
.text:0040AAD1 008 mov dword_418820, esi
.text:0040AAD7 008 push offset dword_418820
.text:0040AADC 00C mov eax, [ecx]
.text:0040AADE 00C call dword ptr [eax+2Ch]

At this point, you have control of ECX (esp+8 is your address data). The 
data from the packet is stored in memory and is relatively static (see 
NOTE). The address is then loaded into EAX, and then called as EAX+2Ch, 
which is controllable data from the packet. In this code, I just jump ahead 
to the portbinding shellcode.
The following exploit opens up a shell on port 4444:

This vulnerability leads to remote code execution.

Risk Level:

CA has been notified


[Shirkdog Security]

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