Vulnerabilities > CVE-2019-5477 - OS Command Injection vulnerability in multiple products

047910
CVSS 9.8 - CRITICAL
Attack vector
NETWORK
Attack complexity
LOW
Privileges required
NONE
Confidentiality impact
HIGH
Integrity impact
HIGH
Availability impact
HIGH
network
low complexity
nokogiri
canonical
debian
CWE-78
critical
nessus

Summary

A command injection vulnerability in Nokogiri v1.10.3 and earlier allows commands to be executed in a subprocess via Ruby's `Kernel.open` method. Processes are vulnerable only if the undocumented method `Nokogiri::CSS::Tokenizer#load_file` is being called with unsafe user input as the filename. This vulnerability appears in code generated by the Rexical gem versions v1.0.6 and earlier. Rexical is used by Nokogiri to generate lexical scanner code for parsing CSS queries. The underlying vulnerability was addressed in Rexical v1.0.7 and Nokogiri upgraded to this version of Rexical in Nokogiri v1.10.4.

Vulnerable Configurations

Part Description Count
Application
Nokogiri
238
OS
Canonical
4
OS
Debian
2

Common Attack Pattern Enumeration and Classification (CAPEC)

  • Command Line Execution through SQL Injection
    An attacker uses standard SQL injection methods to inject data into the command line for execution. This could be done directly through misuse of directives such as MSSQL_xp_cmdshell or indirectly through injection of data into the database that would be interpreted as shell commands. Sometime later, an unscrupulous backend application (or could be part of the functionality of the same application) fetches the injected data stored in the database and uses this data as command line arguments without performing proper validation. The malicious data escapes that data plane by spawning new commands to be executed on the host.
  • Command Delimiters
    An attack of this type exploits a programs' vulnerabilities that allows an attacker's commands to be concatenated onto a legitimate command with the intent of targeting other resources such as the file system or database. The system that uses a filter or a blacklist input validation, as opposed to whitelist validation is vulnerable to an attacker who predicts delimiters (or combinations of delimiters) not present in the filter or blacklist. As with other injection attacks, the attacker uses the command delimiter payload as an entry point to tunnel through the application and activate additional attacks through SQL queries, shell commands, network scanning, and so on.
  • Exploiting Multiple Input Interpretation Layers
    An attacker supplies the target software with input data that contains sequences of special characters designed to bypass input validation logic. This exploit relies on the target making multiples passes over the input data and processing a "layer" of special characters with each pass. In this manner, the attacker can disguise input that would otherwise be rejected as invalid by concealing it with layers of special/escape characters that are stripped off by subsequent processing steps. The goal is to first discover cases where the input validation layer executes before one or more parsing layers. That is, user input may go through the following logic in an application: In such cases, the attacker will need to provide input that will pass through the input validator, but after passing through parser2, will be converted into something that the input validator was supposed to stop.
  • Argument Injection
    An attacker changes the behavior or state of a targeted application through injecting data or command syntax through the targets use of non-validated and non-filtered arguments of exposed services or methods.
  • OS Command Injection
    In this type of an attack, an adversary injects operating system commands into existing application functions. An application that uses untrusted input to build command strings is vulnerable. An adversary can leverage OS command injection in an application to elevate privileges, execute arbitrary commands and compromise the underlying operating system.

Nessus

  • NASL familyFreeBSD Local Security Checks
    NASL idFREEBSD_PKG_0569146EBDEF11E9BD318DE4A4470BBB.NASL
    descriptionNokogiri GitHub release : A command injection vulnerability in Nokogiri v1.10.3 and earlier allows commands to be executed in a subprocess by Ruby
    last seen2020-06-01
    modified2020-06-02
    plugin id127876
    published2019-08-14
    reporterThis script is Copyright (C) 2019-2020 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/127876
    titleFreeBSD : Nokogiri -- injection vulnerability (0569146e-bdef-11e9-bd31-8de4a4470bbb)
  • NASL familyUbuntu Local Security Checks
    NASL idUBUNTU_USN-4175-1.NASL
    descriptionIt was discovered that Nokogiri incorrectly handled inputs. A remote attacker could possibly use this issue to execute arbitrary OS commands. Note that Tenable Network Security has extracted the preceding description block directly from the Ubuntu security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.
    last seen2020-06-01
    modified2020-06-02
    plugin id130588
    published2019-11-06
    reporterUbuntu Security Notice (C) 2019 Canonical, Inc. / NASL script (C) 2019 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/130588
    titleUbuntu 16.04 LTS / 18.04 LTS / 19.04 / 19.10 : ruby-nokogiri vulnerability (USN-4175-1)
  • NASL familyDebian Local Security Checks
    NASL idDEBIAN_DLA-1933.NASL
    descriptionA command injection vulnerability in Nokogiri allows commands to be executed in a subprocess by Ruby
    last seen2020-06-01
    modified2020-06-02
    plugin id129363
    published2019-09-26
    reporterThis script is Copyright (C) 2019 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/129363
    titleDebian DLA-1933-1 : ruby-nokogiri security update