PHP iconv Stream Filter Denial of Service Vulnerability [CVE-2018-10546]

A vulnerability in the convert.iconv source code of PHP could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on a targeted system.

The vulnerability exists because the iconv stream filter used by the affected software does not reject invalid multibyte sequences. An attacker could exploit this vulnerability by submitting malicious input to a targeted system. A successful exploit could trigger an infinite loop condition in the convert.iconvsource code file of the affected software and consume excessive amounts of CPU resources, resulting in a DoS condition.

Proof-of-concept (PoC) code that demonstrates an exploit of this vulnerability is publicly available.

PHP has confirmed the vulnerability and released software updates.

CVE Number – CVE-2018-10546

• To exploit this vulnerability, the attacker must be able to send malicious input to the targeted system, making exploitation more difficult in environments that restrict network access from untrusted sources.

• Administrators are advised to apply the appropriate updates.

  Administrators are advised to allow only trusted users to have network access.

  Administrators are advised to run both firewall and antivirus applications to minimize the potential of inbound and outbound threats.

  Administrators may consider using IP-based access control lists (ACLs) to allow only trusted systems to access the affected systems.

  Administrators can help protect affected systems from external attacks by using a solid firewall strategy.

  Administrators are advised to monitor affected systems.

• PHP has released a bug report and changelogs at the following links: Bug #76249, PHP 5 ChangeLog, and PHP 7 ChangeLog

• PHP has released software updates at the following link: PHP 5.6.36, 7.1.17, and 7.2.5

  
  
  
  
  

Duncan

Duncan is a technology professional with over 20 years experience of working in various IT roles. He has a interest in cyber security, and has a wide range of other skills in radio, electronics and telecommunications.