REDHAT-BUG-711245
First published: Mon Jun 06 2011(Updated: )
It was found that vsftpd, Very Secure FTP daemon, when the network namespace (CONFIG_NET_NS) support was activated in the kernel, used to create a new network namespace per connection. A remote attacker could use this flaw to cause memory pressure (kernel OOM killer protection mechanism to be activated and potentially terminate vsftpd or arbitrary [vsftpd independent] process, which satisfied the OOM killer process selection algorithm). References: [1] <a href="http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=629373">http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=629373</a> [2] <a href="https://bugs.launchpad.net/ubuntu/+source/linux/+bug/720095">https://bugs.launchpad.net/ubuntu/+source/linux/+bug/720095</a> Public PoC (from [2]): ====================== The test is started in this way: $ for i in 1 2 3 4 5 6 7 8 ; do ./feedftp $i >/dev/null & done What is observed during the test is that /proc/vmallocinfo grows continually with lines like the following being added: 0xffffe8ffff800000-0xffffe8ffffa00000 2097152 pcpu_get_vm_areas+0x0/0x790 vmalloc 0xffffe8ffffa00000-0xffffe8ffffc00000 2097152 pcpu_get_vm_areas+0x0/0x790 vmalloc 0xffffe8ffffc00000-0xffffe8ffffe00000 2097152 pcpu_get_vm_areas+0x0/0x790 vmalloc vsftpd bug: <a class="bz_bug_link bz_status_CLOSED bz_closed bz_public " title="CLOSED NOTABUG - vsftpd: Do not create network namespace per connection" href="show_bug.cgi?id=711134">https://bugzilla.redhat.com/show_bug.cgi?id=711134</a> Proposed patches (but has connection rates problem): <a href="http://patchwork.ozlabs.org/patch/88217/">http://patchwork.ozlabs.org/patch/88217/</a>
| Affected Software | Affected Version | How to fix |
|---|---|---|
| vsftpd |
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Reference Links
- http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=629373
- https://bugs.launchpad.net/ubuntu/+source/linux/+bug/720095
- https://bugzilla.redhat.com/show_bug.cgi/show_bug.cgi?id=711134
- http://patchwork.ozlabs.org/patch/88217/
- https://bugzilla.redhat.com/show_bug.cgi/show_bug.cgi?id=749061
- https://bugzilla.redhat.com/show_bug.cgi/show_bug.cgi?id=711134#c16
- https://bugzilla.redhat.com/show_bug.cgi?id=711245
Frequently Asked Questions
What is the severity of REDHAT-BUG-711245?
The severity of REDHAT-BUG-711245 is considered high due to the potential for a remote attacker to exploit the memory pressure condition.
How do I fix REDHAT-BUG-711245?
To fix REDHAT-BUG-711245, update vsftpd to the latest version that includes security patches addressing this vulnerability.
What versions of vsftpd are affected by REDHAT-BUG-711245?
All versions of vsftpd that have the CONFIG_NET_NS support activated in the kernel are potentially affected by REDHAT-BUG-711245.
Can REDHAT-BUG-711245 lead to a denial of service attack?
Yes, REDHAT-BUG-711245 can lead to a denial of service attack by exhausting system memory and triggering the kernel OOM killer.
Is my system at risk if I'm using vsftpd with network namespaces?
Yes, if you are using vsftpd with network namespaces enabled, your system may be at risk due to the vulnerability described in REDHAT-BUG-711245.
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