We can confirm this. We have been seeing this activity targeting various parts of WorldNet's netblock. Most of the sources are originating from the 209.x.x.x range. Closer examination of the sources reveal that they are all what look like default installations of Linux (Redhat in particular). We believe this may be a new worm (or scanning tool) to look for/exploit the recent samba vulnerabilities. We think the point of the syn/fin packets are to determine whether the remote host has port 139 open, and whether the host is running windows (with netbios-ssn open), or is a linux machine running samba. Most stateful inspection firewalls will drop these SYN/Fin packets, but they are a clever way to determine the OS of an unfirewalled host. The fact that the source port of these packets is 139 is highly suspicious as well. .. We are in the progress of setting a honeypot in an attempt to 'infect' ourselves, I will keep the list informed of anything else we discover. If anyone else has access to machine they think may be infected with this worm, please let me know. Kevin Hodle CCNA, Network+, A+ Alexander Open Systems Network Operations Center (913)-307-2366 kevinhat_private -----Original Message----- From: Skip Carter [mailto:skipat_private] Sent: Friday, April 18, 2003 1:52 PM To: incidentsat_private Subject: port 139 syn-fin scans Hello, We have been seeing some persistant scanning activity for the past week. When we first saw it, we thought it was just an isolated incident, but in the last couple of days we have been seeing more of the same thing. The scans are on TCP port 139 with SYN-FIN flags set and both the source and destination ports set to 139. The scans attempt to hide by being slow (our /24 gets hit roughly once every 45 minutes) and by using a randomized target address. We have only seen a couple of source addresses for the probes, but they all have the same signature. Snort reports: [**] [111:13:1] (spp_stream4) STEALTH ACTIVITY (SYN FIN scan) detection [**] 04/18-00:59:44.192258 aaa.bbb.ccc.ddd:139 -> eee.fff.ggg.hhh:139 TCP TTL:30 TOS:0x0 ID:39426 IpLen:20 DgmLen:40 ******SF Seq: 0x1E68EED0 Ack: 0x4B9A8F9A Win: 0x404 TcpLen: 20 Are any others seeing this ? ---------------------------------------------------------------------------- Attend Black Hat Briefings & Training Europe, May 12-15 in Amsterdam, the world's premier event for IT and network security experts. The two-day Training features 6 hand-on courses on May 12-13 taught by professionals. The two-day Briefings on May 14-15 features 24 top speakers with no vendor sales pitches. Deadline for the best rates is April 25. Register today to ensure your place. http://www.securityfocus.com/BlackHat-incidents ----------------------------------------------------------------------------
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