Ruby 1.9.3/2.0.0/2.1.1/2.1.2/2.1.3 REXML Parser resource consumption

HistoryDiffrelatejsonxmlCTI

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
4.6	$0-$5k	0.00

Summaryinfo

A vulnerability was found in Ruby 1.9.3/2.0.0/2.1.1/2.1.2/2.1.3. It has been classified as problematic. Affected by this vulnerability is an unknown functionality of the component REXML Parser. This manipulation causes resource consumption. This vulnerability is handled as CVE-2014-8080. There is not any exploit available. Applying a patch is the recommended action to fix this issue.

Detailsinfo

A vulnerability was found in Ruby 1.9.3/2.0.0/2.1.1/2.1.2/2.1.3 (Programming Language Software). It has been declared as problematic. Affected by this vulnerability is an unknown code block of the component REXML Parser. The manipulation with an unknown input leads to a resource consumption vulnerability. The CWE definition for the vulnerability is CWE-400. The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources. As an impact it is known to affect availability. The summary by CVE is:

The REXML parser in Ruby 1.9.x before 1.9.3-p550, 2.0.x before 2.0.0-p594, and 2.1.x before 2.1.4 allows remote attackers to cause a denial of service (memory consumption) via a crafted XML document, aka an XML Entity Expansion (XEE) attack.

The weakness was released 10/27/2014 by Willis Vandevanter and Nir Goldshlager as Denial of Service XML Expansion as confirmed advisory (Website). The advisory is shared at ruby-lang.org. This vulnerability is known as CVE-2014-8080 since 10/09/2014. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Neither technical details nor an exploit are publicly available. Responsible for the vulnerability is the following code:

require 'rexml/document'

xml = <<XML
<!DOCTYPE root [
  # ENTITY expansion vector
]>
<cd></cd>
XML

p REXML::Document.new(xml)

The advisory points out:

When reading text nodes from an XML document, the REXML parser can be coerced into allocating extremely large string objects which can consume all of the memory on a machine, causing a denial of service.

The vulnerability scanner Nessus provides a plugin with the ID 79642 (CentOS 6 : ruby (CESA-2014:1911)), which helps to determine the existence of the flaw in a target environment. It is assigned to the family CentOS Local Security Checks. The commercial vulnerability scanner Qualys is able to test this issue with plugin 195659 (Ubuntu Security Notification for Ruby1.8, Ruby1.9.1, Ruby2.0, Ruby2.1 Vulnerabilities (USN-2397-1)).

Applying the patch 1.9.3 Patchlevel 550/2.0.0 Patchlevel 594/2.1.4 is able to eliminate this problem. The vulnerability will be addressed with the following lines of code:

class REXML::Entity
  def value
      if @value
        matches = @value.scan(PEREFERENCE_RE)
        rv = @value.clone
        if @parent
          sum = 0
          matches.each do |entity_reference|
            entity_value = @parent.entity( entity_reference[0] )
            if sum + entity_value.bytesize > Document.entity_expansion_text_limit
              raise "entity expansion has grown too large"
            else
              sum += entity_value.bytesize
            end
            rv.gsub!( /%#{entity_reference.join};/um, entity_value )
          end
        end
        return rv
      end
      nil
   end
end

The vulnerability is also documented in the databases at X-Force (98494), Tenable (79642), SecurityFocus (BID 70935†), Secunia (SA61607†) and SecurityTracker (ID 1031166†). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Productinfo

Type

Programming Language Software

Name

Ruby

Version

License

open-source

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.3
VulDB Meta Temp Score: 4.6

VulDB Base Score: 5.3
VulDB Temp Score: 4.6
VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv2info

AV	AC	Au	C	I	A
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💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock

VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

NVD Base Score: 🔍

Exploitinginfo

Class: Resource consumption
CWE: CWE-400 / CWE-404
CAPEC: 🔍
ATT&CK: 🔍

Physical: No
Local: No
Remote: Yes

Availability: 🔍
Status: Unproven

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Nessus ID: 79642
Nessus Name: CentOS 6 : ruby (CESA-2014:1911)
Nessus File: 🔍
Nessus Risk: 🔍
Nessus Family: 🔍
Nessus Port: 🔍

OpenVAS ID: 14611
OpenVAS Name: Amazon Linux Local Check: ALAS-2014-441
OpenVAS File: 🔍
OpenVAS Family: 🔍

Qualys ID: 🔍
Qualys Name: 🔍

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Patch
Status: 🔍

0-Day Time: 🔍

Patch: 1.9.3 Patchlevel 550/2.0.0 Patchlevel 594/2.1.4

Timelineinfo

10/09/2014 🔍
10/27/2014 +18 days 🔍
10/27/2014 +0 days 🔍
10/29/2014 +2 days 🔍
11/03/2014 +5 days 🔍
11/03/2014 +0 days 🔍
11/04/2014 +1 days 🔍
11/05/2014 +1 days 🔍
12/02/2014 +27 days 🔍
10/01/2015 +303 days 🔍
02/24/2022 +2338 days 🔍

Sourcesinfo

Advisory: Denial of Service XML Expansion
Researcher: Willis Vandevanter, Nir Goldshlager
Status: Confirmed
Confirmation: 🔍

CVE: CVE-2014-8080 (🔍)
GCVE (CVE): GCVE-0-2014-8080
GCVE (VulDB): GCVE-100-68101

OVAL: 🔍

X-Force: 98494 - Ruby REXML parser denial of service, Medium Risk
SecurityFocus: 70935 - Ruby CVE-2014-8080 XML External Entity Denial of Service Vulnerability
Secunia: 61607 - Ruby REXML XML Entity Expansion Denial of Service Vulnerability, Less Critical
SecurityTracker: 1031166
Vulnerability Center: 53088 - Ruby REXML parser Remote DoS Vulnerability via a Crafted XML Document, Medium

Entryinfo

Created: 11/05/2014 10:52
Updated: 02/24/2022 02:57
Changes: 11/05/2014 10:52 (76), 02/01/2018 07:27 (14), 02/24/2022 02:57 (3)
Complete: 🔍
Cache ID: 216:D1C:103

If you want to get the best quality for vulnerability data then you always have to consider VulDB.

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