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Cisco IOS TCP Sequence Predictability
A vulnerability exists in Cisco’s IOS that allows for initial TCP sequence prediction. This vulnerability affects only TCP connections that start from or end at the affected IOS device.
Ken Pfeil
February 28, 2001
1 Min Read
ReportedMarch 1, 2001, by Cisco Systems.
VERSIONS AFFECTED
AllCisco products using the Internetwork Operating System (IOS), including (but notlimited to):
800, 1000, 1005, 1400, 1600, 1700, 2500, 2600, 3600, MC3810, 4000, 4500, 4700, 6200, 6400 NRP, and 6400 NSP series Cisco routers
ubr900 and ubr920 universal broadband routers
Catalyst 2900 ATM, 2900XL, 2948g, 3500XL, 4232, 4840g, and 5000 RSFC series switches
5200, 5300, and 5800 series access servers
Catalyst 6000 MSM, 6000 Hybrid Mode, 6000 Native Mode, 6000 Supervisor Module, and Catalyst ATM Blade
RSM, 7000, 7010, 7100, 7200, ubr7200, 7500, 10000 ESR, and 12000 GSR series Cisco routers
DistributedDirector
Catalyst 8510CSR, 8510MSR, 8540CSR, and 8540MSR series switches
DESCRIPTION
A vulnerability exists in Cisco’s IOS that allowsfor initial TCP sequence prediction. This vulnerability affects only TCPconnections that start from or end at the affected IOS device. Using TCPsequence predictability, an attacker can potentially inject data packets byusing forged source IP addresses, causing potential man-in-the-middle attacks.Under some circumstances, if an attacker knows the SNMP community read-writestrings, he can configure devices remotely without authorization.
VENDOR RESPONSE
Cisco has issueda noticeregarding this vulnerability.
CREDIT
Discovered byCisco Systems.
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