lighttpd HTTP GET Request Signed Integer Overflow Denial of Service Vulnerability [CVE-2019-11072]

CVE Number – CVE-2019-11072

A vulnerability in lighttpd could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on a targeted system.

The vulnerability is due to improper handling of HTTP GET requests by the burl_normalize_2F_to_slash_fix function, as defined in the burl.c source code file of the affected software, when the url-path-2f-decode option is enabled. An attacker could exploit this vulnerability by sending a request that submits malicious input to the targeted system. A successful exploit could cause the affected application to crash, resulting in a DoS condition, or cause other unspecified impacts, which could allow the attacker to conduct further attacks.Proof-of-concept (PoC) code that demonstrates an exploit of this vulnerability is publicly available.The vendor has confirmed the vulnerability and released software updates.

Analysis

• To exploit this vulnerability, an 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

• The vendor has released a bug report at the following link: Bug #2945

Fixed Software

• The vendor has released software updates at the following link: Fix abort in http-parseopts (fixes #2945)