R7-0016: Sybase ASE 12.5 Remote Password Array Denial of Service
To: email@example.com Date: Thu, 20 Nov 2003 12:15:57 -0800
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Rapid7, Inc. Security Advisory
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Rapid7 Advisory R7-0016
Sybase ASE 12.5 Remote Password Array Denial of Service
Published: November 20, 2003
1. Affected system(s):
o Sybase 12.5 ASE for Windows
o Sybase 12.5 ASE for Linux
Apparently NOT VULNERABLE:
o Sybase 126.96.36.199 for Linux
Sybase Adaptive Server Enterprise (ASE) 12.5 is susceptible to a
denial of service attack when a login is made with an invalid
remote password array. A valid login is required to exploit
3. Vendor status and information
The vendor has been notified and has released an ESD
(Electronic Software Distribution) which fixes this issue.
Upgrade to Sybase ASE 12.5 ESD#2 or higher.
5. Detailed analysis
Connecting to Sybase Adaptive Server Enterprise (ASE) 12.5 with
a valid login (correct user ID and password) and an invalid remote
password array causes an access violation on the server, resulting
in a denial of service in the child thread or process. On
Windows, which spawns threads for each client, the server will
stop responding to all commands, including new login requests.
On systems such as Linux, which spawns new child processes for each
client, other clients do not appear to be affected. However, an
attacker could cause an effective DoS on new clients by rapidly
exploiting new child processes as they are launched, denying other
clients the ability to log in.
The remote password array is included in the TDS LOGINREC structure
and is of the format:
byte first server name length
byte[ ] first server name
byte first password length
byte[ ] first password
byte next server name length
byte total length of remote password array
By specifying invalid lengths, a heap overflow can be triggered.
We believe the possibility of arbitrary remote code execution is
unlikely in this case, but the possibility has not been ruled out.
6. Contact Information
Rapid7 Security Advisories
Phone: +1 (212) 558-8700
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This advisory Copyright (C) 2003 Rapid7, Inc. Permission is
hereby granted to redistribute this advisory, providing that no
changes are made and that the copyright notices and disclaimers
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