Denial of Service (DoS)

Affecting github.com/pires/go-proxyproto package, versions <0.5.0

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Overview

github.com/pires/go-proxyproto is a Go library implementation of the PROXY protocol, versions 1 and 2.

Affected versions of this package are vulnerable to Denial of Service (DoS) via the parseVersion1() function.

The reader in this package is a default bufio.Reader wrapping a net.Conn. It will read from the connection until it finds a newline. Since no limits are implemented in the code, a deliberately malformed V1 header could be used to exhaust memory in a server process using this code - and create a DoS. This can be exploited by sending a stream starting with PROXY and continuing to send data (which does not contain a newline) until the target stops acknowledging.

The risk here is small, because only trusted sources should be allowed to send proxy protocol headers.

Details

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

Remediation

Upgrade github.com/pires/go-proxyproto to version 0.5.0 or higher.

References

CVSS Score

4.4
medium severity
  • Attack Vector
    Network
  • Attack Complexity
    High
  • Privileges Required
    High
  • User Interaction
    None
  • Scope
    Unchanged
  • Confidentiality
    None
  • Integrity
    None
  • Availability
    High
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H
Credit
Iestyn Elfick
CVE
CVE-2021-23351
CWE
CWE-400
Snyk ID
SNYK-GOLANG-GITHUBCOMPIRESGOPROXYPROTO-1081577
Disclosed
03 Mar, 2021
Published
07 Mar, 2021