The Computer Associates License Client/Server applications provide a
method for CA products to register their licenses on the network. The
License Client and Server are distributed with almost all CA software
distributions. More information about Computer Associates software
products is available from:
Remote exploitation of a buffer overflow vulnerability in Computer
Associates License Server and License Client can allow attackers to
execute arbitrary code.
The vulnerability specifically exists due to insufficient bounds
checking on user-supplied values in GCR requests. The GCR request
packet format is shown below:
A0 GCR HOSTNAME<DEVBOX>HARDWARE<001122334455>LOCALE<English>
OS<Windows_NT 5.0>OLFFILE<0 0 0>SERVER<RMT>VERSION<3 1.54.0>
NETWORK<127.0.0.1 HOSTNAME 255.255.255.0>MACHINE<PC_1586_1_3201>
CHECKSUMS<1 2 3 4 5 6 7 8 9 10 11 12>RMTV<1.00><EOM>
If the second, fifth, eighth, or eleventh field of the Checksums item
contains a large string, a stack overflow will occur. The format
specifier for the call to sscanf() is simply:
"%x %s %i %x %s %i %x %s %i %x %s %i"
If the eleventh field is used to overflow the local stack buffer, the
return address will be overwritten with the address at 64 bytes into
the overflow string.
Ollydbg output after SEH overwrite in CA License Client:
ECX 7C91056D ntdll.7C91056D
EBX 00D4E053 ASCII "GCR"
ESP 0082FC10 ASCII "XXXXXXXXXXXXXXXXXXXXXXXXXXXXX
EBP 00D4E050 ASCII "A0"
ESI 0082FCBC ASCII "XXXXXXXXXXXXXXXXXXXXXXXXXXXXX
EDI 00D4E057 ASCII "HOSTNAME<DEVBOX>HARDWARE<0011
Log data, item 0
Message=Access violation when executing [DEADC0DE]
Exploitation allows remote attackers to execute arbitrary code under
the privileges of Local System. A GETCONFIG packet exchange which
discloses the remote operating system version usually proceeds the GCR
request and increases the likelihood of successful exploitation. The CA
License Server does not run by default, but is packaged with most
Computer Associates software distributions. The CA License Client does
run by default and is packaged with almost all Computer Associates
iDEFENSE has confirmed that CA License Server 0.1.0.15 and CA License
Client 0.1.0.15 are vulnerable.
Use a firewall to only allow trusted hosts to connect to the Computer
Associates License Server and Client ports.
A vendor advisory for this issue is available at:
Patches for this issue are available at:
The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CAN-2005-0581 to this issue. This is a candidate for inclusion in
the CVE list (http://cve.mitre.org), which standardizes names for
security problems. This is one of several overflows that have been
12/01/2004 Initial vendor notification
12/01/2004 Initial vendor response
03/02/2005 Coordinated public disclosure
An anonymous contributor is credited with discovering this
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Copyright © 2005 Verisign, Inc.
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