J-Security Center

Title: Multiple Vendor TCP Initial Sequence Number Statistical Vulnerability

Severity: HIGH

Description:

Over the past several years, a variety of attacks against TCP initial sequence number (ISN) generation have been discussed.

A vulnerability exists in some TCP/IP stack implementations that use random increments for initial sequence numbers. Such implementations are vulnerable to statistical attack, which could allow an attacker to predict, within a reasonable range, sequence numbers of future and existing connections.

The weakness is due to the implications of the Central Limit Theorem, which roughly states that the distribution of the sum of a large number of independent, identically distributed variables will be approximately normal, regardless of the underlying distribution.

According to the TCP protocol, a packet from a remote host with the correct sequence number is trusted to come from that host. By predicting a sequence number, several attacks could be performed; an attacker could disrupt or hijack existing connections, or spoof future connections.

The practical impact of the attack depends on the target protocol. Most importantly, systems running insecure protocols which blindly trust a TCP connection which appears to come from a given IP address without requiring any other form of authentication are vulnerable to spoofing by a remote attacker, potentially yielding privileges or access on the system.

Affected Products:

  • Apple Mac OS 7 7.0.0
  • Apple Mac OS 7 7.0.1
  • Apple Mac OS 7 7.1.0
  • Apple Mac OS 7 7.1.2
  • Apple Mac OS 7 7.5.1
  • Apple Mac OS 7 7.5.2
  • Apple Mac OS 7 7.5.3
  • Apple Mac OS 7 7.6.0
  • Apple Mac OS 7 7.6.1
  • Apple Mac OS 8 8.0.0
  • Apple Mac OS 8 8.1.0
  • Apple Mac OS 8 8.5.0
  • Apple Mac OS 8 8.6.0
  • Apple Mac OS 9 9.0.0
  • Apple Mac OS 9 9.0.4
  • Apple Mac OS 9 9.1.0
  • Apple Mac OS X 10.0.0
  • Apple Mac OS X 10.0.1
  • Apple Mac OS X 10.0.2
  • Avaya DefinityOne Media Servers
  • Avaya IP600 Media Servers
  • Avaya S3400 Message Application Server
  • Avaya S8100 Media Servers
  • BSDI BSD/OS 3.0.0
  • BSDI BSD/OS 4.0.0
  • Cisco IOS 11.0
  • Cisco IOS 11.1
  • Cisco IOS 11.1AA
  • Cisco IOS 11.1CA
  • Cisco IOS 11.1CC
  • Cisco IOS 11.1CT
  • Cisco IOS 11.1IA
  • Cisco IOS 11.2
  • Cisco IOS 11.2(4)XA
  • Cisco IOS 11.2(9)XA
  • Cisco IOS 11.2BC
  • Cisco IOS 11.2F
  • Cisco IOS 11.2GS
  • Cisco IOS 11.2P
  • Cisco IOS 11.2SA
  • Cisco IOS 11.2WA3
  • Cisco IOS 11.3
  • Cisco IOS 11.3(2)XA
  • Cisco IOS 11.3AA
  • Cisco IOS 11.3DA
  • Cisco IOS 11.3DB
  • Cisco IOS 11.3HA
  • Cisco IOS 11.3MA
  • Cisco IOS 11.3NA
  • Cisco IOS 11.3T
  • Cisco IOS 11.3WA4
  • Cisco IOS 12.0
  • Cisco IOS 12.0DA
  • Cisco IOS 12.0DB
  • Cisco IOS 12.0DC
  • Cisco IOS 12.0S
  • Cisco IOS 12.0SC
  • Cisco IOS 12.0SL
  • Cisco IOS 12.0ST
  • Cisco IOS 12.0SX
  • Cisco IOS 12.0T
  • Cisco IOS 12.0W5
  • Cisco IOS 12.0WT
  • Cisco IOS 12.0XA
  • Cisco IOS 12.0XB
  • Cisco IOS 12.0XC
  • Cisco IOS 12.0XD
  • Cisco IOS 12.0XE
  • Cisco IOS 12.0XF
  • Cisco IOS 12.0XG
  • Cisco IOS 12.0XH
  • Cisco IOS 12.0XI
  • Cisco IOS 12.0XJ
  • Cisco IOS 12.0XK
  • Cisco IOS 12.0XL
  • Cisco IOS 12.0XM
  • Cisco IOS 12.0XN
  • Cisco IOS 12.0XP
  • Cisco IOS 12.0XQ
  • Cisco IOS 12.0XR
  • Cisco IOS 12.0XS
  • Cisco IOS 12.0XU
  • Cisco IOS 12.0XV
  • Cisco IOS 12.1
  • Cisco IOS 12.1AA
  • Cisco IOS 12.1CX
  • Cisco IOS 12.1DA
  • Cisco IOS 12.1DB
  • Cisco IOS 12.1DC
  • Cisco IOS 12.1E
  • Cisco IOS 12.1EC
  • Cisco IOS 12.1EX
  • Cisco IOS 12.1T
  • Cisco IOS 12.1XA
  • Cisco IOS 12.1XB
  • Cisco IOS 12.1XC
  • Cisco IOS 12.1XD
  • Cisco IOS 12.1XE
  • Cisco IOS 12.1XF
  • Cisco IOS 12.1XG
  • Cisco IOS 12.1XH
  • Cisco IOS 12.1XI
  • Cisco IOS 12.1XJ
  • Cisco IOS 12.1XK
  • Cisco IOS 12.1XL
  • Cisco IOS 12.1XM
  • Cisco IOS 12.1XP
  • Cisco IOS 12.1XQ
  • Cisco IOS 12.1XR
  • Cisco IOS 12.1XS
  • Cisco IOS 12.1XT
  • Cisco IOS 12.1XU
  • Cisco IOS 12.1XV
  • Cisco IOS 12.1XW
  • Cisco IOS 12.1XX
  • Cisco IOS 12.1XY
  • Cisco IOS 12.1XZ
  • Cisco IOS 12.1YA
  • Cisco IOS 12.1YB
  • Cisco IOS 12.1YC
  • Cisco IOS 12.1YD
  • FreeBSD FreeBSD 3.5.0 -STABLEpre050201
  • FreeBSD FreeBSD 4.2.0 -STABLEpre050201
  • HP HP-UX 10.0.0
  • HP HP-UX 10.20.0
  • HP HP-UX 11.0.0
  • HP HP-UX 11.0.0 4
  • HP HP-UX 11.11.0
  • IBM AIX 4.3.0
  • Linux kernel 2.0.0 .x
  • Linux kernel 2.1.0 .x
  • Microsoft Windows 95
  • Microsoft Windows 98
  • Microsoft Windows 98SE
  • Microsoft Windows NT 4.0
  • Microsoft Windows NT 4.0 SP1
  • Microsoft Windows NT 4.0 SP2
  • Microsoft Windows NT 4.0 SP3
  • Microsoft Windows NT 4.0 SP4
  • Microsoft Windows NT 4.0 SP5
  • Microsoft Windows NT 4.0 SP6
  • Microsoft Windows NT Enterprise Server 4.0
  • Microsoft Windows NT Enterprise Server 4.0 SP1
  • Microsoft Windows NT Enterprise Server 4.0 SP2
  • Microsoft Windows NT Enterprise Server 4.0 SP3
  • Microsoft Windows NT Enterprise Server 4.0 SP4
  • Microsoft Windows NT Enterprise Server 4.0 SP5
  • Microsoft Windows NT Enterprise Server 4.0 SP6
  • Microsoft Windows NT Enterprise Server 4.0 SP6a
  • Microsoft Windows NT Server 4.0
  • Microsoft Windows NT Server 4.0 SP1
  • Microsoft Windows NT Server 4.0 SP2
  • Microsoft Windows NT Server 4.0 SP3
  • Microsoft Windows NT Server 4.0 SP4
  • Microsoft Windows NT Server 4.0 SP5
  • Microsoft Windows NT Server 4.0 SP6
  • Microsoft Windows NT Server 4.0 SP6a
  • Microsoft Windows NT Terminal Server 4.0
  • Microsoft Windows NT Terminal Server 4.0 SP1
  • Microsoft Windows NT Terminal Server 4.0 SP2
  • Microsoft Windows NT Terminal Server 4.0 SP3
  • Microsoft Windows NT Terminal Server 4.0 SP4
  • Microsoft Windows NT Terminal Server 4.0 SP5
  • Microsoft Windows NT Terminal Server 4.0 SP6
  • Microsoft Windows NT Workstation 4.0
  • Microsoft Windows NT Workstation 4.0 SP1
  • Microsoft Windows NT Workstation 4.0 SP2
  • Microsoft Windows NT Workstation 4.0 SP3
  • Microsoft Windows NT Workstation 4.0 SP4
  • Microsoft Windows NT Workstation 4.0 SP5
  • Microsoft Windows NT Workstation 4.0 SP6
  • Microsoft Windows NT Workstation 4.0 SP6a
  • OpenBSD OpenBSD 2.8.0
  • SGI IRIX 6.5.0
  • SGI IRIX 6.5.1
  • SGI IRIX 6.5.10
  • SGI IRIX 6.5.10 f
  • SGI IRIX 6.5.10 m
  • SGI IRIX 6.5.11
  • SGI IRIX 6.5.11 f
  • SGI IRIX 6.5.11 m
  • SGI IRIX 6.5.12
  • SGI IRIX 6.5.12 f
  • SGI IRIX 6.5.12 m
  • SGI IRIX 6.5.13
  • SGI IRIX 6.5.13 f
  • SGI IRIX 6.5.13 m
  • SGI IRIX 6.5.14
  • SGI IRIX 6.5.14 f
  • SGI IRIX 6.5.14 m
  • SGI IRIX 6.5.2
  • SGI IRIX 6.5.2 f
  • SGI IRIX 6.5.2 m
  • SGI IRIX 6.5.3
  • SGI IRIX 6.5.3 f
  • SGI IRIX 6.5.3 m
  • SGI IRIX 6.5.4
  • SGI IRIX 6.5.4 f
  • SGI IRIX 6.5.4 m
  • SGI IRIX 6.5.5
  • SGI IRIX 6.5.5 f
  • SGI IRIX 6.5.5 m
  • SGI IRIX 6.5.6
  • SGI IRIX 6.5.6 f
  • SGI IRIX 6.5.6 m
  • SGI IRIX 6.5.7
  • SGI IRIX 6.5.7 f
  • SGI IRIX 6.5.7 m
  • SGI IRIX 6.5.8
  • SGI IRIX 6.5.8 f
  • SGI IRIX 6.5.8 m
  • SGI IRIX 6.5.9
  • SGI IRIX 6.5.9 f
  • SGI IRIX 6.5.9 m
  • Sun Solaris 7.0

References:

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