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Message-ID: <Y6ItNDy/+sfibmNL@gentoo.org>
Date: Tue, 20 Dec 2022 15:46:28 -0600
From: John Helmert III <ajak@...too.org>
To: oss-security@...ts.openwall.com
Cc: ovs-discuss <ovs-discuss@...nvswitch.org>, i.maximets@....org,
Aaron Conole <aconole@...hat.com>,
Qian Chen <cq674350529@...il.com>
Subject: Re: [ADVISORY] LLDP underflow while parsing malformed
Auto Attach TLV (Open vSwitch)
On Tue, Dec 20, 2022 at 10:39:23PM +0100, Ilya Maximets wrote:
> Description
> ===========
>
> Multiple versions of Open vSwitch are vulnerable to crafted LLDP
> packets causing denial of service, and data underflow attacks.
> Triggering the vulnerabilities requires LLDP processing to be enabled
> for a specific port. Open vSwitch versions prior to 2.4.0 are not
> vulnerable.
>
> The Common Vulnerabilities and Exposures project (cve.mitre.org)
> did not assign the identifier to this issue yet. The identifier will
> be communicated separately.
Has a CVE been requested?
> This issue does not affect the `lldpd' project, although they share
> a code base. The issue is related to parsing the Auto Attach TLVs,
> which is specific to the Open vSwitch implementation.
>
>
> Mitigation
> ==========
>
> For any version of Open vSwitch, preventing LLDP packets from reaching
> Open vSwitch mitigates the vulnerability. We do not recommend
> attempting to mitigate the vulnerability this way because of the
> following difficulties:
>
> - Open vSwitch obtains packets before the iptables host firewall,
> so ebtables on the Open vSwitch host cannot ordinarily block the
> vulnerability.
>
> - If Open vSwitch is configured to receive and transmit LLDP
> messages, the required functionality will need to be disabled
> potentially disrupting the network.
>
> We have found that Open vSwitch is subject to a denial of service, and
> possibly a remote code execution exploit when LLDP processing is enabled
> on an interface. By default, interfaces are not configured to process
> LLDP messages.
>
>
> Fix
> ===
>
> Patches to fix these vulnerabilities in Open vSwitch 2.13.x and newer are
> applied to the appropriate branches, and the original patch is located
> at:
>
> https://mail.openvswitch.org/pipermail/ovs-dev/2022-December/400596.html
>
> Recommendation
> ==============
>
> We recommend that users of Open vSwitch apply the respective patch, or
> upgrade to a known patched version of Open vSwitch. These include:
>
> * 3.0.3
> * 2.17.5
> * 2.16.6
> * 2.15.7
> * 2.14.8
> * 2.13.10
>
>
> Acknowledgments
> ===============
>
> The Open vSwitch team wishes to thank the reporter:
>
> Qian Chen <cq674350529@...il.com>
>
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