Denial of Service (DoS) Affecting mailsplit package, versions <4.2.1

mailsplit is an email parser.

Affected versions of this package are vulnerable to Denial of Service (DoS) attacks via a crafted email containing a few million multiparts.

MIME (Multipurpose Internet Mail Extentions) is an internet standard that extends the format of email to support: Non-ACSII character sets, non-text attachments, and more.

Most Node.js MIME decoders do not validate the number of multiparts they are willing to decode, allowing an attacker to send a crafted email containing a few million multiparts, which will then block the Node.js event loop for tens of seconds, explode RAM usage, and cause an out of memory crash.

• April 23rd, 2018 - Initial private disclosure to package owner
• April 24th, 2018 - Initial response from package owner
• June 25th, 2018 - Public disclosure

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its intended and legitimate users.

Unlike other vulnerabilities, DoS attacks usually do not aim at breaching security. Rather, they are focused on making websites and services unavailable to genuine users resulting in downtime.

One popular Denial of Service vulnerability is DDoS (a Distributed Denial of Service), an attack that attempts to clog network pipes to the system by generating a large volume of traffic from many machines.

When it comes to open source libraries, DoS vulnerabilities allow attackers to trigger such a crash or crippling of the service by using a flaw either in the application code or from the use of open source libraries.

Two common types of DoS vulnerabilities:

• High CPU/Memory Consumption- An attacker sending crafted requests that could cause the system to take a disproportionate amount of time to process. For example, commons-fileupload:commons-fileupload.

• Crash - An attacker sending crafted requests that could cause the system to crash. For Example, npm ws package