Vulnerabilities > CVE-2008-5162 - Use of Insufficiently Random Values vulnerability in Freebsd

047910
CVSS 7.0 - HIGH
Attack vector
LOCAL
Attack complexity
HIGH
Privileges required
LOW
Confidentiality impact
HIGH
Integrity impact
HIGH
Availability impact
HIGH
local
high complexity
freebsd
CWE-330

Summary

The arc4random function in the kernel in FreeBSD 6.3 through 7.1 does not have a proper entropy source for a short time period immediately after boot, which makes it easier for attackers to predict the function's return values and conduct certain attacks against the GEOM framework and various network protocols, related to the Yarrow random number generator.

Vulnerable Configurations

Part Description Count
OS
Freebsd
42

Common Weakness Enumeration (CWE)

Common Attack Pattern Enumeration and Classification (CAPEC)

  • Brute Force
    In this attack, some asset (information, functionality, identity, etc.) is protected by a finite secret value. The attacker attempts to gain access to this asset by using trial-and-error to exhaustively explore all the possible secret values in the hope of finding the secret (or a value that is functionally equivalent) that will unlock the asset. Examples of secrets can include, but are not limited to, passwords, encryption keys, database lookup keys, and initial values to one-way functions. The key factor in this attack is the attackers' ability to explore the possible secret space rapidly. This, in turn, is a function of the size of the secret space and the computational power the attacker is able to bring to bear on the problem. If the attacker has modest resources and the secret space is large, the challenge facing the attacker is intractable. While the defender cannot control the resources available to an attacker, they can control the size of the secret space. Creating a large secret space involves selecting one's secret from as large a field of equally likely alternative secrets as possible and ensuring that an attacker is unable to reduce the size of this field using available clues or cryptanalysis. Doing this is more difficult than it sounds since elimination of patterns (which, in turn, would provide an attacker clues that would help them reduce the space of potential secrets) is difficult to do using deterministic machines, such as computers. Assuming a finite secret space, a brute force attack will eventually succeed. The defender must rely on making sure that the time and resources necessary to do so will exceed the value of the information. For example, a secret space that will likely take hundreds of years to explore is likely safe from raw-brute force attacks.
  • Signature Spoofing by Key Recreation
    An attacker obtains an authoritative or reputable signer's private signature key by exploiting a cryptographic weakness in the signature algorithm or pseudorandom number generation and then uses this key to forge signatures from the original signer to mislead a victim into performing actions that benefit the attacker.
  • Session Credential Falsification through Prediction
    This attack targets predictable session ID in order to gain privileges. The attacker can predict the session ID used during a transaction to perform spoofing and session hijacking.

Seebug

bulletinFamilyexploit
descriptionBUGTRAQ ID: 32447 CVE(CAN) ID: CVE-2008-5162 FreeBSD就是一种运行在Intel平台上、可以自由使用的开放源码Unix类系统。 FreeBSD内核中广泛使用arc4random(9)随机数生成器,一些应用依赖于该随机数生成器的加密强度。arc4random(9)定期用来自FreeBSD内核的Yarrow随机数生成器的熵重新提供种子,Yarrow随机数生成器从包括硬件中断等各种来源收集熵。在引导阶段,从用户域向Yarrow随机数生成器提供了额外的,以确保加密中有足够的熵。 在初始化arc4random(9)随机数生成器时,可能没有足够多的熵来满足依赖于arc4random(9)的内核系统的需求,且arc4random(9)可能需要5分钟的时间才能用来自Yarrow随机数生成器的安全熵重新获得种子,因此在引导后的300秒内或耗尽64k随机数据之前,所有依赖于高质量随机数生成器的安全相关内核子系统都受各种攻击的影响,攻击者可以相对较容易的破解加密算法,导致恢复加密数据、猜测进程ID或执行DNS缓存破坏等各种结果。 FreeBSD FreeBSD 7.0 FreeBSD FreeBSD 6.3 FreeBSD ------- FreeBSD已经为此发布了一个安全公告(FreeBSD-SA-08:11)以及相应补丁: FreeBSD-SA-08:11:arc4random(9) predictable sequence vulnerability 链接:<a href=ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-08:11.arc4random.asc target=_blank>ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-08:11.arc4random.asc</a> 补丁下载: [FreeBSD 7.x] # fetch <a href=http://security.FreeBSD.org/patches/SA-08:11/arc4random.patch target=_blank>http://security.FreeBSD.org/patches/SA-08:11/arc4random.patch</a> # fetch <a href=http://security.FreeBSD.org/patches/SA-08:11/arc4random.patch.asc target=_blank>http://security.FreeBSD.org/patches/SA-08:11/arc4random.patch.asc</a> [FreeBSD 6.x] # fetch <a href=http://security.FreeBSD.org/patches/SA-08:11/arc4random6x.patch target=_blank>http://security.FreeBSD.org/patches/SA-08:11/arc4random6x.patch</a> # fetch <a href=http://security.FreeBSD.org/patches/SA-08:11/arc4random6x.patch.asc target=_blank>http://security.FreeBSD.org/patches/SA-08:11/arc4random6x.patch.asc</a>
idSSV:4496
last seen2017-11-19
modified2008-11-26
published2008-11-26
reporterRoot
titleFreeBSD arc4random (9)伪随机数生成器不充分漏洞