EEYE: CA BrightStor ArcServe Backup Server Arbitrary Pointer Dereference

["eEye Advisories" <eEyeAdvisories () eeye com>]

CA BrightStor ARCserve Backup Server Arbitrary Pointer Dereference

Release Date:
October 11, 2007

Date Reported:
June 18, 2007

Severity:
High (Remote Code Execution)

Vendor:
Computer Associates (CA)

Systems Affected:
BrightStor ARCserve Backup 11.5
BrightStor ARCserve Backup 11.1
BrightStor ARCserve Backup 11.0
BrightStor ARCserve Backup 10.5
BrightStor ARCserve Backup 9.01

Overview:
eEye Digital Security has discovered a remote vulnerability in CA
BrightStor ARCserve Backup Server that allows an attacker to execute
arbitrary code as SYSTEM without any user interaction.  The exploit is
extremely reliable and can be successfully delivered either across the
internet or within local networks via a random TCP port that is
disclosed by the BrightStor portmapper service on TCP/111.

Technical Details:
A remote vulnerability lies within Queue.dll (Version 11.5.4402.15 and
prior) when handling a malformed ONRPC protocol request sent to CA
BrightStor's ARCserve Backup message queuing service, LQserver.exe.
BrightStor uses a protocol similar to a simplified version of RPC called
ONCRPC (Open Network Computing Remote Procedure Calls) and is described
in the following RFCs: 1831, 1833, and 1832.  This vulnerability is only
achieved by calling operation 0x76 (Data Queue Request) under the
process id of 0x0006097d (LQserver.exe's unique Proc ID).  After
initiating this procedure, LQServer.exe then calls the vulnerable DLL
file, Queue.dll. This procedure inadvertently processes user supplied
data and then references that data as variables without any form of
sanitation of verification.  This is demonstrated below:

<lqserver.exe>
100161B0        MOV EDX,DWORD PTR DS:[ECX+4]    ; Move Arbitrary Pointer
#2 into EDX
100161B3        PUSH EDX                                ; Push Arbitrary
Pointer #2 onto the Stack
100161B4        MOV EAX,DWORD PTR SS:[EBP+8]    ; Move (0x0113F8A8 the
address to Arbitrary
                                                        ; Pointer #1)
into EAX
100161B7        MOV ECX,DWORD PTR DS:[EAX]      ; Move Arbitrary Pointer
#1 into ECX
100161B9        PUSH ECX                                ; Push Arbitrary
Pointer #1 onto the Stack
100161BA        CALL QUEUE.10012816             ; CALL Vulnerable DLL
...
<queue.dll>
1001281C        CMP DWORD PTR SS:[EBP+8],0      ; EBP + 8 points to
Arbitrary Pointer #1  - This makes 
                                                        ; sure our
pointer isn't NULL.
10012820        JNZ SHORT QUEUE.10012829        ; Since our pointer
isn't NULL we jump
10012829        MOV EAX,DWORD PTR SS:[EBP+8]    ; Load Arbitrary Pointer
#1 into EAX
1001282C        MOV DWORD PTR SS:[EBP-4],EAX    ; Write Arbitrary
Pointer into EBP-4 (0x00D39618)
1001282F        CMP DWORD PTR DS:[10037884],0   ; This checks for an
error message field - NULL 
                                                        ; signifies 'The
operation completed successfully'
10012836        JE SHORT QUEUE.10012870         ; Jump is taken
10012870        MOV EAX,DWORD PTR SS:[EBP+C]    ; Move Arbitrary Pointer
#2 into EAX
10012873        PUSH EAX                                ; Push Arbitrary
Pointer #2 onto the stack
10012874        PUSH QUEUE.10037884             ; Push NULL
10012879        MOV ECX,DWORD PTR SS:[EBP-4]    ; Move Arbitrary Pointer
#1 into ECX
1001287C        MOV EDX,DWORD PTR DS:[ECX]      ; Move Arbitrary Pointer
#1 into EDX
1001287E        MOV ECX,DWORD PTR SS:[EBP-4]    ; Move Arbitrary Pointer
#1 into ECX
10012881        CALL DWORD PTR DS:[EDX]         ; Call Arbitrary Pointer
#1

At this point Arbitrary Pointer #1 is referenced and called by
Queue.dll, which can then in turn can reference Arbitrary Pointer #2.
After referencing Arbitrary Pointer #2, an attacker can completely
control code execution and redirect Queue.dll to execute to their own
payload.  After exploitation, LQserver.exe crashes and must be manually
restarted by the "CA Domain Server" service.


Protection:
Blink - Unified Client Security has proactively protected from these
vulnerabilities since their discovery.
Retina - Network Security Scanner has been updated to identify these
vulnerabilities.

Vendor Status:
Computer Associates released patches for these vulnerabilities. These
patches are available here:
http://supportconnectw.ca.com/public/storage/infodocs/basb-secnotice.asp

Credit:
Greg Linares

Greetings:
Big thanks to Dre and his underappreciated development software, The
Super Soeder Bros, Master Chief Maiffret, Silva, Casey, Will, H5N1,
Apocalypse Survivor Normalboy, Laughing Man, Jerome Athias, Roland and
Waldorf Music Gear, and to all the Giraffes In Wheelchairs.

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Related Links:
Preview - Advanced Security Intelligence - http://www.eeye.com/preview
Retina - Network Security Scanner - Free Trial:
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Blink - Unified Client Security Personal - Free For Home Use:
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Blink - Unified Client Security Professional - Free Trial:
http://www.eeye.com/html/products/blink/download/index.html

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