A vulnerability in the Secure Sockets Layer (SSL) packet reassembly functionality of the detection engine in Cisco Firepower System Software could allow an unauthenticated, remote attacker to cause the detection engine to consume excessive system memory on an affected device, which could cause a denial of service (DoS) condition. The vulnerability is due to the affected software improperly handling changes to SSL connection states. An attacker could exploit this vulnerability by sending crafted SSL connections through an affected device. A successful exploit could allow the attacker to cause the detection engine to consume excessive system memory on the affected device, which could cause a DoS condition. The device may need to be reloaded manually to recover from this condition. Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability. This advisory is available at the following link: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180418-fpsnort
This vulnerability affects Cisco Firepower System Software Releases 6.0.0 and later, if the software is configured as described in this section and the software is running on any of the following Cisco products:
A device is vulnerable if the software is configured to pass encrypted traffic that matches an SSL policy rule or has a default rule action of Do not decrypt.
To determine which Cisco Firepower System Software release is running on a device, administrators can log in to the device and use the show version command in the CLI. The following example shows the output of the command for a device that is running Release 6.2.0:
Vulmon
> show version
---------------------[ ftd ]---------------------
Model : Cisco ASA5525-X Threat Defense (75) Version 6.2.0 (Build 362)
UUID : 2849ba3c-ecb8-11e6-98ca-b9fc2975893c
Rules update version : 2017-03-15-001-vrt
VDB version : 279
----------------------------------------------------
No other Cisco products are currently known to be affected by this vulnerability.
Cisco has confirmed that this vulnerability does not affect the following Cisco products:
This vulnerability could cause the Snort process to exhaust system memory on an affected device and restart. While the Snort process is restarting, threat detection could be bypassed, inspection of all network traffic could fail, or network traffic could be prevented from passing through the device, depending on the platform and device configuration.
On Cisco FirePOWER platforms:
On Cisco ASA 5500-X Series Firewalls with FirePOWER Services, traffic will bypass threat detection and will not be dropped, if the sfr fail-open CLI command is supported and configured on the ASA.
Exploitation of this vulnerability could cause the following error message to appear in the /var/log/messages system log file for an affected device:
Firepower-module2 kernel: [109568.659049] snort invoked oom-killer: gfp_mask=0xd0, order=0, oom_score_adj=0
Contact the Cisco Technical Assistance Center (TAC) if additional assistance is required to determine whether the device has been compromised by this vulnerability.
Cisco has released free software updates that address the vulnerability described in this advisory. Customers may only install and expect support for software versions and feature sets for which they have purchased a license. By installing, downloading, accessing, or otherwise using such software upgrades, customers agree to follow the terms of the Cisco software license:
https://www.cisco.com/c/en/us/products/end-user-license-agreement.html
Additionally, customers may only download software for which they have a valid license, procured from Cisco directly, or through a Cisco authorized reseller or partner. In most cases this will be a maintenance upgrade to software that was previously purchased. Free security software updates do not entitle customers to a new software license, additional software feature sets, or major revision upgrades.
When considering software upgrades, customers are advised to regularly consult the advisories for Cisco products, which are available from the Cisco Security Advisories and Alerts page, to determine exposure and a complete upgrade solution.
In all cases, customers should ensure that the devices to be upgraded contain sufficient memory and confirm that current hardware and software configurations will continue to be supported properly by the new release. If the information is not clear, customers are advised to contact the Cisco Technical Assistance Center (TAC) or their contracted maintenance providers.
Customers Without Service Contracts
Customers who purchase directly from Cisco but do not hold a Cisco service contract and customers who make purchases through third-party vendors but are unsuccessful in obtaining fixed software through their point of sale should obtain upgrades by contacting the Cisco TAC:
https://www.cisco.com/c/en/us/support/web/tsd-cisco-worldwide-contacts.html
Customers should have the product serial number available and be prepared to provide the URL of this advisory as evidence of entitlement to a free upgrade.
Customers should upgrade to an appropriate release as indicated in the table in this section. To help ensure a complete upgrade solution, consider that this advisory is part of a collection that includes the following advisories:
In the following table, the left column lists releases of Cisco software. The center column indicates whether a release is affected by the vulnerability described in this advisory and the first release that includes the fix for this vulnerability. The right column indicates whether a release is affected by all the vulnerabilities described in this collection of advisories and which release includes fixes for those vulnerabilities.
| Cisco Firepower System Software | First Fixed Release for This Vulnerability | First Fixed Release for All Vulnerabilities Described in the Collection of Advisories |
|---|---|---|
| 6.0 | 6.1.0.6 | 6.1.0.6 |
| 6.0.1 | 6.1.0.6 | 6.1.0.6 |
| 6.1.0 | 6.1.0.6 or later | 6.1.0.6 |
| 6.2.0 | 6.2.0.3 or later | 6.2.0.5 |
| 6.2.1 | Not vulnerable | 6.2.2.1 |
| 6.2.2 | Not vulnerable | 6.2.2.1 |
| 6.2.3 | Not vulnerable | 6.2.3 |
The Cisco Product Security Incident Response Team (PSIRT) is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory.
This vulnerability was found during the resolution of a Cisco TAC support case.
To learn about Cisco security vulnerability disclosure policies and publications, see the Security Vulnerability Policy. This document also contains instructions for obtaining fixed software and receiving security vulnerability information from Cisco.
| Version | Description | Section | Status | Date |
|---|---|---|---|---|
| 1.2 | Added the Cisco bug identifier CSCve23031. | Final | 2020-May-18 | |
| 1.1 | Updated internal metadata release information. | - | Final | 2019-November-19 |
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