JRuby before 1.6.5.1 computes hash values without restricting the ability to trigger hash collisions predictably, which allows context-dependent attackers to cause a denial of service (CPU consumption) via crafted input to an application that maintains a hash table.

JRuby before 1.6.5.1 computes hash values without restricting the ability to trigger hash collisions predictably, which allows context-dependent attackers to cause a denial of service (CPU consumption) via crafted input to an application that maintains a hash table. Note: This update includes corrections to the original fix for later Debian releases to avoid the issues identified in CVE-2012-5370.

NOTE: Tenable Network Security has extracted the preceding description block directly from the DLA security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

The remote host is affected by the vulnerability described in GLSA-201207-06 (JRuby: Denial of Service)

    JRuby does not properly randomize hash functions to protect against hash       collision attacks.
  Impact :

    A remote attacker could send a specially crafted input, possibly       resulting in a Denial of Service condition.
  Workaround :

    There is no known workaround at this time.

oCERT reports :

A variety of programming languages suffer from a denial-of-service (DoS) condition against storage functions of key/value pairs in hash data structures, the condition can be leveraged by exploiting predictable collisions in the underlying hashing algorithms.

The issue finds particular exposure in web server applications and/or frameworks. In particular, the lack of sufficient limits for the number of parameters in POST requests in conjunction with the predictable collision properties in the hashing functions of the underlying languages can render web applications vulnerable to the DoS condition. The attacker, using specially crafted HTTP requests, can lead to a 100% of CPU usage which can last up to several hours depending on the targeted application and server performance, the amplification effect is considerable and requires little bandwidth and time on the attacker side.

The condition for predictable collisions in the hashing functions has been reported for the following language implementations : Java, JRuby, PHP, Python, Rubinius, Ruby. In the case of the Ruby language, the 1.9.x branch is not affected by the predictable collision condition since this version includes a randomization of the hashing function.

The vulnerability outlined in this advisory is practically identical to the one reported in 2003 and described in the paper Denial of Service via Algorithmic Complexity Attacks which affected the Perl language.

ID	Name	Product	Family	Severity
83142	Debian DLA-209-1 : jruby security update	Nessus	Debian Local Security Checks	high
59898	GLSA-201207-06 : JRuby: Denial of Service	Nessus	Gentoo Local Security Checks	high
57552	FreeBSD : Multiple implementations -- DoS via hash algorithm collision (91be81e7-3fea-11e1-afc7-2c4138874f7d)	Nessus	FreeBSD Local Security Checks	high

Detections

Analytics

CVE-2011-4838

high

Tenable Plugins

high

high

high