Exim CVE-2019-16928 Heap Buffer Overflow Vulnerability

Description

Exim is prone to a heap-based buffer-overflow vulnerability. Successfully exploiting this issue allows attackers to execute arbitrary code in the context of the affected application. Failed exploits will result in denial-of-service conditions. Exim versions 4.92 through 4.92.2 are vulnerable…

Technologies Affected

• Exim Exim 4.92
• Exim Exim 4.92.1
• Exim Exim 4.92.2

Recommendations

Block external access at the network boundary, unless external parties require service.
If global access isn’t needed, filter access to the affected computer at the network boundary. Restricting access to only trusted computers and networks might greatly reduce the likelihood of successful exploits.

Run all software as a nonprivileged user with minimal access rights.
To limit the potential damage that a successful exploit may achieve, run all nonadministrative software as a regular user with the least amount of privileges required to successfully operate.

Deploy network intrusion detection systems to monitor network traffic for malicious activity.
Deploy NIDS to monitor network traffic for signs of anomalous or suspicious activity. This includes but is not limited to requests that include NOP sleds and unexplained incoming and outgoing traffic. This may indicate exploit attempts or activity that results from a successful exploit.

Implement multiple redundant layers of security.
Various memory-protection schemes (such as nonexecutable and randomly mapped memory segments) may hinder an attacker’s ability to exploit this vulnerability to execute arbitrary code.

Updates are available. Please see the references or vendor advisory for more information.