Michael Rash, Security Researcher

Software Release - psad-2.2.1

psad-2.2.1 released The 2.2.1 release of psad is available for download. This release adds new support for detecting a type of scan that psad has been previously blind to - IP protocol scanning (nmap -sO). Also in this release is the ability to detect Topera IPv6 scans and differentiate them from Nmap IPv6 scans. Other important changes include a new test suite, email throttling, and auto blocking timeouts that can be set for each danger level. Here is the complete ChangeLog:

  • Added IP protocol scan detection (nmap -sO). A new psad.conf variable PROTOCOL_SCAN_THRESHOLD defines the minimum number of different IP protocols (default = 5) that must be scanned before an alert is triggered.
  • Added detection for Topera IPv6 scans when --log-ip-options is used in the ip6tables logging rule. When this option is not used, the previous psad-2.2 release detected Topera scans. An example TCP SYN packet generated by Topera when --log-ip-options is used looks like this (note the series of empty IP options strings "OPT ( )":
    Dec 20 20:10:40 rohan kernel: [  488.495776] DROP IN=eth0 OUT=
    DST=2012:1234:1234:0000:0000:0000:0000:0002 LEN=132 TC=0 HOPLIMIT=64
    FLOWLBL=0 OPT ( ) OPT ( ) OPT ( ) OPT ( ) OPT ( ) OPT ( ) OPT ( )
    OPT ( ) OPT ( ) PROTO=TCP SPT=61287 DPT=1 WINDOW=8192 RES=0x00 SYN
  • Bug fix in --Analyze mode when IP fields are to be searched with the --analysis-fields argument (such as --analysis-fields "SRC:"). The bug was reported by Gregorio Narvaez, and looked like this:
    Use of uninitialized value $_[0] in length at
    ../../blib/lib/NetAddr/IP/ (autosplit into
    ../../blib/lib/auto/NetAddr/IP/UtilPP/ line 126.
    Use of uninitialized value $_[0] in length at
    ../../blib/lib/NetAddr/IP/ (autosplit into
    ../../blib/lib/auto/NetAddr/IP/UtilPP/ line 126.
    Bad argument length for NetAddr::IP::UtilPP::hasbits, is 0, should be
    128 at ../../blib/lib/NetAddr/IP/ (autosplit into
    ../../blib/lib/auto/NetAddr/IP/UtilPP/ line 122.
  • Added --stdin argument to allow psad to collect iptables log data from STDIN in --Analyze mode. This makes it easier to run an iptables logs through psad from arbitrary files like so:
    # grep "IN=.*OUT=" /var/log/kern.log | psad -A --stdin
  • Added the ability to acquire Snort rule 'msg' fields from fwsnort if it's also installed. A new variable FWSNORT_RULES_DIR tells psad where to look for the fwsnort rule set. This fixes a problem reported by Pui Edylie to the psad mailing list where fwsnort logged an attack that psad could not map back to a descriptive 'msg' field.
  • Added the ability to set per-danger level timeouts when psad is configured to run in auto-blocking mode. These timeouts are implemented with new AUTO_BLOCK_DL*_TIMEOUT variables - one for each of the five possible danger levels that may be assigned to a scanning IP address.
  • Added the ability to throttle emails generated by psad via a new EMAIL_THROTTLE variable which is implemented as a per-IP threshold. That is, if EMAIL_THROTTLE is set to "10", then psad will only send 1/10th as many emails for each scanning IP as it would have normally.
The complete psad-2.2.1 ChangeLog can also be found here via the psad gitweb interface.