Vulnerabilities > CVE-2015-1417 - Resource Exhaustion vulnerability in Freebsd
Attack vector
NETWORK Attack complexity
LOW Privileges required
NONE Confidentiality impact
NONE Integrity impact
NONE Availability impact
HIGH Summary
The inet module in FreeBSD 10.2x before 10.2-PRERELEASE, 10.2-BETA2-p2, 10.2-RC1-p1, 10.1x before 10.1-RELEASE-p16, 9.x before 9.3-STABLE, 9.3-RELEASE-p21, and 8.x before 8.4-STABLE, 8.4-RELEASE-p35 on systems with VNET enabled and at least 16 VNET instances allows remote attackers to cause a denial of service (mbuf consumption) via multiple concurrent TCP connections.
Vulnerable Configurations
| Part | Description | Count |
|---|---|---|
| OS | 56 |
Common Weakness Enumeration (CWE)
Common Attack Pattern Enumeration and Classification (CAPEC)
- XML Ping of the Death An attacker initiates a resource depletion attack where a large number of small XML messages are delivered at a sufficiently rapid rate to cause a denial of service or crash of the target. Transactions such as repetitive SOAP transactions can deplete resources faster than a simple flooding attack because of the additional resources used by the SOAP protocol and the resources necessary to process SOAP messages. The transactions used are immaterial as long as they cause resource utilization on the target. In other words, this is a normal flooding attack augmented by using messages that will require extra processing on the target.
- XML Entity Expansion An attacker submits an XML document to a target application where the XML document uses nested entity expansion to produce an excessively large output XML. XML allows the definition of macro-like structures that can be used to simplify the creation of complex structures. However, this capability can be abused to create excessive demands on a processor's CPU and memory. A small number of nested expansions can result in an exponential growth in demands on memory.
- Inducing Account Lockout An attacker leverages the security functionality of the system aimed at thwarting potential attacks to launch a denial of service attack against a legitimate system user. Many systems, for instance, implement a password throttling mechanism that locks an account after a certain number of incorrect log in attempts. An attacker can leverage this throttling mechanism to lock a legitimate user out of their own account. The weakness that is being leveraged by an attacker is the very security feature that has been put in place to counteract attacks.
- Violating Implicit Assumptions Regarding XML Content (aka XML Denial of Service (XDoS)) XML Denial of Service (XDoS) can be applied to any technology that utilizes XML data. This is, of course, most distributed systems technology including Java, .Net, databases, and so on. XDoS is most closely associated with web services, SOAP, and Rest, because remote service requesters can post malicious XML payloads to the service provider designed to exhaust the service provider's memory, CPU, and/or disk space. The main weakness in XDoS is that the service provider generally must inspect, parse, and validate the XML messages to determine routing, workflow, security considerations, and so on. It is exactly these inspection, parsing, and validation routines that XDoS targets. There are three primary attack vectors that XDoS can navigate Target CPU through recursion: attacker creates a recursive payload and sends to service provider Target memory through jumbo payloads: service provider uses DOM to parse XML. DOM creates in memory representation of XML document, but when document is very large (for example, north of 1 Gb) service provider host may exhaust memory trying to build memory objects. XML Ping of death: attack service provider with numerous small files that clog the system. All of the above attacks exploit the loosely coupled nature of web services, where the service provider has little to no control over the service requester and any messages the service requester sends.
Nessus
| NASL family | FreeBSD Local Security Checks |
| NASL id | FREEBSD_PKG_0CB9D5BB600A11E6A6C314DAE9D210B8.NASL |
| description | There is a mistake with the introduction of VNET, which converted the global limit on the number of segments that could belong to reassembly queues into a per-VNET limit. Because mbufs are allocated from a global pool, in the presence of a sufficient number of VNETs, the total number of mbufs attached to reassembly queues can grow to the total number of mbufs in the system, at which point all network traffic would cease. Impact : An attacker who can establish concurrent TCP connections across a sufficient number of VNETs and manipulate the inbound packet streams such that the maximum number of mbufs are enqueued on each reassembly queue can cause mbuf cluster exhaustion on the target system, resulting in a Denial of Service condition. As the default per-VNET limit on the number of segments that can belong to reassembly queues is 1/16 of the total number of mbuf clusters in the system, only systems that have 16 or more VNET instances are vulnerable. |
| last seen | 2020-06-01 |
| modified | 2020-06-02 |
| plugin id | 92891 |
| published | 2016-08-12 |
| reporter | This script is Copyright (C) 2016-2018 and is owned by Tenable, Inc. or an Affiliate thereof. |
| source | https://www.tenable.com/plugins/nessus/92891 |
| title | FreeBSD : FreeBSD -- Resource exhaustion in TCP reassembly (0cb9d5bb-600a-11e6-a6c3-14dae9d210b8) |
| code | |