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Geo++(R) GNCASTER: Insecure handling of long URLs

During a penetration test, RedTeam Pentesting discovered that the GNCASTER software does not handle long URLs correctly. An attacker can use this to crash the server software or potentially execute code on the server.


  • Product: Geo++(R) GNCASTER
  • Affected Versions: <=
  • Fixed Versions:
  • Vulnerability Type: Memory corruption
  • Security Risk: high
  • Vendor URL:
  • Vendor Status: notified
  • Advisory URL:
  • Advisory Status: published
  • CVE: CVE-2010-0552
  • CVE URL:


“Geo++(R) GNCASTER is the Geo++ implementation of a NTRIP caster. NTRIP is a protocol within RTCM to provide GNSS information via Internet.”

(from the vendor’s homepage)

More Details

The GNCaster software allows communication with clients through a subset of the HTTP protocol. If an attacker sends an HTTP GET request for a nonexistent URL path and the request is less than 988 bytes long, the server reacts with an HTTP 404 error and the message

File "/AAAAAA[...]AAAA" not found on this server.

If the URL path length is 988 bytes or more, the HTTP 404 error is still returned but the server thread stops before returning the message above.

If attackers send a sequence of such requests in quick succession, the server can be reproducibly crashed. RedTeam Pentesting believes it is also possible to exploit this vulnerability to execute code on the server.

Proof of Concept

The following command can be used to crash the server if it is called multiple times:

$ curl -i "`perl -e 'printf "A"x988'`"


A vulnerable server could be protected from this vulnerability by an application layer firewall that filters overly long HTTP GET requests.


Update GNCASTER to version

Security Risk

This vulnerability can be used for very efficient DoS attacks. This is especially serious as GNCaster is a real time application that is typically used by multiple mobile clients that rely on a functioning server. The vulnerability could potentially also be leveraged to remote code execution on the server. The risk is therefore regarded as high.


  • 2009-07-06 Vulnerability identified during a penetration test
  • 2009-07-14 Meeting with customer
  • 2009-12-01 Vendor releases fixed version
  • 2010-01-27 Advisory released
  • 2011-09-07 CVE information added

RedTeam Pentesting GmbH

RedTeam Pentesting offers individual penetration tests, short pentests, performed by a team of specialised IT-security experts. Hereby, security weaknesses in company networks or products are uncovered and can be fixed immediately.

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