PyYAML yaml.load() API Arbitrary Code Execution Vulnerability [CVE-2017-18342]

CVE Number – CVE-2017-18342

A vulnerability in the yaml.load() API of PyYAML could allow an unauthenticated, remote attacker to execute arbitrary code on a targeted system.

The vulnerability exists because the yaml.load() of the affected software does not call yaml.safe_load(), making the API unsafe to use. An attacker could exploit this vulnerability by submitting untrusted input. A successful exploit could allow the attacker to execute arbitrary code on the targeted system.

The vendor confirmed the vulnerability and released software updates.

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

Vendor Announcements
Fixed Software
  • The vendor released a software update at the following link: PyYAML 4.1




Duncan Newell

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

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