SSLsplit - tool for man-in-the-middle attacks against SSL/TLS encrypted network connections

SSLsplit is a tool for man-in-the-middle attacks against SSL/TLS encrypted network connections. Connections are transparently intercepted through a network address translation engine and redirected to SSLsplit. SSLsplit terminates SSL/TLS and initiates a new SSL/TLS connection to the original destination address, while logging all data transmitted. SSLsplit is intended to be useful for network forensics and penetration testing.

SSLsplit supports plain TCP, plain SSL, HTTP and HTTPS connections over both IPv4 and IPv6. For SSL and HTTPS connections, SSLsplit generates and signs forged X509v3 certificates on-the-fly, based on the original server certificate subject DN and subjectAltName extension. SSLsplit fully supports Server Name Indication (SNI) and is able to work with RSA, DSA and ECDSA keys and DHE and ECDHE cipher suites. SSLsplit can also use existing certificates of which the private key is available, instead of generating forged ones. SSLsplit supports NULL-prefix CN certificates and can deny OCSP requests in a generic way.

Latest release: sslsplit-0.4.5.tar.bz2 (sslsplit(1))

Usage

% sslsplit -h
Usage: sslsplit [options...] [proxyspecs...]
  -c pemfile  use CA cert (and key) from pemfile to sign forged certs
  -k pemfile  use CA key (and cert) from pemfile to sign forged certs
  -C pemfile  use CA chain from pemfile (intermediate and root CA certs)
  -K pemfile  use key from pemfile for leaf certs (default: generate)
  -t certdir  use cert+chain+key PEM files from certdir to target all sites
              matching the common names (non-matching: generate if CA)
  -O          deny all OCSP requests on all proxyspecs
  -P          passthrough SSL connections if they cannot be split because of
              client cert auth or no matching cert and no CA (default: drop)
  -g pemfile  use DH group params from pemfile (default: keyfiles or auto)
  -G curve    use ECDH named curve (default: secp160r2 for non-RSA leafkey)
  -Z          disable SSL/TLS compression on all connections
  -s ciphers  use the given OpenSSL cipher suite spec (default: ALL:-aNULL)
  -e engine   specify default NAT engine to use (default: ipfw)
  -E          list available NAT engines and exit
  -u user     drop privileges to user (default if run as root: nobody)
  -j jaildir  chroot() to jaildir (default if run as root: /var/empty)
  -p pidfile  write pid to pidfile (default: no pid file)
  -l logfile  connect log: log one line summary per connection to logfile
  -L logfile  content log: full data to file or named pipe (excludes -S)
  -S logdir   content log: full data to separate files in dir (excludes -L)
  -d          daemon mode: run in background, log error messages to syslog
  -D          debug mode: run in foreground, log debug messages on stderr
  -V          print version information and exit
  -h          print usage information and exit
  proxyspec = type listenaddr+port [natengine|targetaddr+port|"sni"+port]
  e.g.        http 0.0.0.0 8080 www.roe.ch 80  # http/4; static hostname dst
              https ::1 8443 2001:db8::1 443   # https/6; static address dst
              https 127.0.0.1 9443 sni 443     # https/4; SNI DNS lookups
              tcp 127.0.0.1 10025              # tcp/4; default NAT engine
              ssl 2001:db8::2 9999 pf          # ssl/6; NAT engine 'pf'
Example:
  sslsplit -k ca.key -c ca.pem -P  https 127.0.0.1 8443  https ::1 8443

See the manual page sslsplit(1) for details on using SSLsplit and setting up the various NAT engines.

Requirements

SSLsplit depends on the OpenSSL and libevent 2.x libraries. The build depends on GNU make and a POSIX.2 environment in PATH. The (optional) unit tests depend on check.

SSLsplit currently supports the following operating systems and NAT engines:

• FreeBSD: pf rdr, ipfw fwd, ipfilter rdr
• OpenBSD: pf rdr
• Linux: netfilter REDIRECT and TPROXY
• Mac OS X: ipfw fwd

Installation

SSLsplit is or will be available as a package or port on the following systems:

• Arch Linux AUR: sslsplit
• Fedora: sslsplit
• Backtrack: sslsplit

To install from source:

make
make test       # optional unit tests
make install    # optional install

Dependencies are autoconfigured using pkg-config. If dependencies are not picked up and fixing PKG_CONFIG_PATH does not help, you can specify their respective locations manually by setting OPENSSL_BASE, LIBEVENT_BASEand/or CHECK_BASE to the respective prefixes.

You can override the default install prefix (/usr/local) by setting PREFIX.

Development

SSLsplit is being developed on Github. For bug reports, please use the Github issue tracker. For patch submissions, please send me pull requests.

https://github.com/droe/sslsplit

You can track releases on freecode (FreshMeat):

http://freecode.com/projects/sslsplit