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Survey of network security systems to counter SIP-based denial-of-service attacks
As described in the above paper:
SIP message payload tampering:
The ﬁrst class of attacks is based on tampering with the actual
SIP message or more speciﬁcally, the SIP payload. SIP is a text-
based protocol and messages are transported usually in clear
text. Attackers can try to inject harmful content into
a message, e.g. by entering meaningless or wrong information
with the goal of exploiting a buffer overﬂow at the target. Also,
such messages can be used to probe for vulnerabilities in the
target. Harmful code that will be executed in an unforeseen
context can be introduced into the payload. An example is SQL
code injection, which allows the attacker to execute SQL code
within a database.
SIP message ﬂow tampering:
A special case of DoS attacks in real time communication
networks are attacks that disturb the ongoing communication
between users. Common internet services like web browsing
or email communication have an asynchronous time model
i.e. a requested web page is directly delivered to a user. The
user will read it without further communication to the web
server. The same applies to email – a user downloads the
email and studies it independently of a server connection. In
contrast, in SIP real time communication networks two
communicating users establish a constant connection with
each other whereby content is transmitted continuously
between both parties.
An attacker can now target this connection by introducing
fake signalling messages into the communication channel.
Several different SIP signalling messages can be misused for
this task. A BYE message with the right credentials can
prematurely terminate a session.
SIP message ﬂooding:
When talking about a DoS attack, one generally means
ﬂooding attacks that overwhelm a victim’s resources. There
are three main resources that can be targeted in a SIP ﬂooding
attack: bandwidth, CPU, or memory.
Source: Ehlert, Sven, Dimitris Geneiatakis, and Thomas Magedanz. "Survey of network security systems to counter SIP-based denial-of-service attacks." Computers & Security 29.2 (2010): 225-243.