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From Cott Lang <c...@internetstaff.com>
Subject mod_jserv/4073: Jserv vulnerable to memory based denial of service attack
Date Wed, 17 Mar 1999 17:36:58 GMT

>Number:         4073
>Category:       mod_jserv
>Synopsis:       Jserv vulnerable to memory based denial of service attack
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    jserv
>State:          open
>Class:          change-request
>Submitter-Id:   apache
>Arrival-Date:   Wed Mar 17 09:40:00 PST 1999
>Last-Modified:
>Originator:     cott@internetstaff.com
>Organization:
apache
>Release:        1.3.3 + 1.0b3
>Environment:
N/A
>Description:
If you send enough connections at Jserv in the sessionTimeout period that
continuously create new sessions (ie, they do not accept/use cookies), 
it's possible to kill JServ with an EOutofMemory exception. Obviously there's
no way to completely prevent this, but it could be made substantially more 
difficult by adding a second much shorter session.timeout value for isNew 
sessions.
>How-To-Repeat:
load jserv with a smaller heap size, set up a bunch of JMeters slamming it
in such a way that sessions are created, you will crash. :)
>Fix:
alter JServServletManager to handle a secondary newsession.timeout (perhaps
a 5 minute default?) and alter run() to:

if((sysMillis - sess.lastAccessTime > sessionTimeout) ||
  ((sess.isNew()) && (sysMillis - sess.lastAccessTime > newSessionTimeout))) {
>Audit-Trail:
>Unformatted:
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