CVE Vulnerabilities


Improper Input Validation

Published: Sep 29, 2017 | Modified: Oct 09, 2019
CVSS 3.x
CVSS 2.x
7.8 HIGH

A vulnerability in the implementation of the PROFINET Discovery and Configuration Protocol (PN-DCP) for Cisco IOS 12.2 through 15.6 could allow an unauthenticated, remote attacker to cause an affected device to reload, resulting in a denial of service (DoS) condition. The vulnerability is due to the improper parsing of ingress PN-DCP Identify Request packets destined to an affected device. An attacker could exploit this vulnerability by sending a crafted PN-DCP Identify Request packet to an affected device and then continuing to send normal PN-DCP Identify Request packets to the device. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition. This vulnerability affects Cisco devices that are configured to process PROFINET messages. Beginning with Cisco IOS Software Release 12.2(52)SE, PROFINET is enabled by default on all the base switch module and expansion-unit Ethernet ports. Cisco Bug IDs: CSCuz47179.


The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.

Affected Software

Name Vendor Start Version End Version
Ios Cisco 15.2(2)e5b 15.2(2)e5b
Ios Cisco 15.0(1)ey 15.0(1)ey
Ios Cisco 15.2(3)ex 15.2(3)ex
Ios Cisco 15.1(2)sg9 15.1(2)sg9
Ios Cisco 15.2(4)ec 15.2(4)ec
Ios Cisco 15.5(3)s2b 15.5(3)s2b
Ios Cisco 15.2(3)e2 15.2(3)e2
Ios Cisco 15.0(2)ey1 15.0(2)ey1
Ios Cisco 15.2(2)e3 15.2(2)e3
Ios Cisco 15.0(2)ec 15.0(2)ec
Ios Cisco 15.2(3)e4 15.2(3)e4
Ios Cisco 12.2(55)se10 12.2(55)se10
Ios Cisco 15.2(2)e6 15.2(2)e6
Ios Cisco 12.4(25e)jao20s 12.4(25e)jao20s
Ios Cisco 12.4(25e)jap1n 12.4(25e)jap1n
Ios Cisco 15.0(2)ey 15.0(2)ey
Ios Cisco 15.0(2)eb 15.0(2)eb
Ios Cisco 15.3(3)jbb6a 15.3(3)jbb6a
Ios Cisco 15.2(3)e5 15.2(3)e5
Ios Cisco 15.2(5a)e1 15.2(5a)e1
Ios Cisco 15.0(2)se4 15.0(2)se4
Ios Cisco 15.0(2)ey2 15.0(2)ey2
Ios Cisco 15.2(2)e2 15.2(2)e2
Ios Cisco 15.6(2)s2 15.6(2)s2
Ios Cisco 15.2(3)e3 15.2(3)e3
Ios Cisco 12.2(55)se9 12.2(55)se9
Ios Cisco 15.6(1)s1a 15.6(1)s1a
Ios Cisco 12.2(55)se7 12.2(55)se7
Ios Cisco 12.2(55)se 12.2(55)se
Ios Cisco 15.2(2)e1 15.2(2)e1
Ios Cisco 15.3(3)jpb 15.3(3)jpb
Ios Cisco 15.0(2)se3 15.0(2)se3
Ios Cisco 15.5(3)s3a 15.5(3)s3a
Ios Cisco 12.2(58)se 12.2(58)se
Ios Cisco 15.2(2)e 15.2(2)e
Ios Cisco 15.2(2)eb2 15.2(2)eb2
Ios Cisco 15.5(3)s2a 15.5(3)s2a
Ios Cisco 15.2(2)eb1 15.2(2)eb1
Ios Cisco 15.0(2)se 15.0(2)se
Ios Cisco 12.2(52)se1 12.2(52)se1
Ios Cisco 15.2(2)eb 15.2(2)eb
Ios Cisco 15.4(3)s6b 15.4(3)s6b
Ios Cisco 15.6(2)sp1c 15.6(2)sp1c
Ios Cisco 15.0(2)se9 15.0(2)se9
Ios Cisco 15.4(3)s7a 15.4(3)s7a
Ios Cisco 12.2(55)se11 12.2(55)se11
Ios Cisco 15.0(2)se2 15.0(2)se2
Ios Cisco 12.2(55)se4 12.2(55)se4
Ios Cisco 15.5(3)s4a 15.5(3)s4a
Ios Cisco 15.2(2)e4 15.2(2)e4
Ios Cisco 15.3(3)jpb2 15.3(3)jpb2
Ios Cisco 12.4(25e)jao3a 12.4(25e)jao3a
Ios Cisco 15.6(2)s0a 15.6(2)s0a
Ios Cisco 15.0(2)se10 15.0(2)se10
Ios Cisco 15.4(3)s5a 15.4(3)s5a
Ios Cisco 12.2(55)se3 12.2(55)se3
Ios Cisco 15.2(1)ey 15.2(1)ey
Ios Cisco 15.0(2)se8 15.0(2)se8
Ios Cisco 15.2(2)e5 15.2(2)e5
Ios Cisco 15.2(5)e2a 15.2(5)e2a
Ios Cisco 15.0(2)se1 15.0(2)se1
Ios Cisco 15.6(2)sp1b 15.6(2)sp1b
Ios Cisco 15.1(2)sg7a 15.1(2)sg7a
Ios Cisco 15.6(2)s3 15.6(2)s3
Ios Cisco 15.2(2a)e2 15.2(2a)e2
Ios Cisco 12.4(25e)jap9 12.4(25e)jap9
Ios Cisco 15.2(2)e5a 15.2(2)e5a
Ios Cisco 15.0(2)se7 15.0(2)se7
Ios Cisco 15.2(3)e1 15.2(3)e1
Ios Cisco 15.0(2)se6 15.0(2)se6
Ios Cisco 15.0(1)ey1 15.0(1)ey1
Ios Cisco 15.5(3)s4d 15.5(3)s4d
Ios Cisco 15.0(1)ey2 15.0(1)ey2
Ios Cisco 12.2(52)se 12.2(52)se
Ios Cisco 12.2(55)se6 12.2(55)se6
Ios Cisco 15.0(2)sqd7 15.0(2)sqd7
Ios Cisco 15.5(3)s4b 15.5(3)s4b
Ios Cisco 15.0(2)se5 15.0(2)se5
Ios Cisco 12.2(58)se2 12.2(58)se2
Ios Cisco 15.0(2)ey3 15.0(2)ey3
Ios Cisco 12.2(55)se5 12.2(55)se5
Ios Cisco 12.2(58)se1 12.2(58)se1
Ios Cisco 15.3(3)jnp2 15.3(3)jnp2
Ios Cisco 15.6(2)sp2a 15.6(2)sp2a
Ios Cisco 15.0(2)se10a 15.0(2)se10a
Ios Cisco 15.3(3)jda3 15.3(3)jda3
Ios Cisco 15.3(3)jc51 15.3(3)jc51
Ios Cisco 15.2(5)e2b 15.2(5)e2b
Ios Cisco 15.3(3)jca7 15.3(3)jca7
Ios Cisco 15.3(3)jnc4 15.3(3)jnc4
Ios Cisco 15.3(3)jpc3 15.3(3)jpc3
Ios Cisco 15.3(3)je1 15.3(3)je1
Ios Cisco 15.3(3)jc7 15.3(3)jc7
Ios Cisco 15.3(3)jc50 15.3(3)jc50
Ios Cisco 15.3(3)jnd2 15.3(3)jnd2

Extended Description

Input validation is a frequently-used technique for checking potentially dangerous inputs in order to ensure that the inputs are safe for processing within the code, or when communicating with other components. When software does not validate input properly, an attacker is able to craft the input in a form that is not expected by the rest of the application. This will lead to parts of the system receiving unintended input, which may result in altered control flow, arbitrary control of a resource, or arbitrary code execution. Input validation is not the only technique for processing input, however. Other techniques attempt to transform potentially-dangerous input into something safe, such as filtering (CWE-790) - which attempts to remove dangerous inputs - or encoding/escaping (CWE-116), which attempts to ensure that the input is not misinterpreted when it is included in output to another component. Other techniques exist as well (see CWE-138 for more examples.) Input validation can be applied to:

Data can be simple or structured. Structured data can be composed of many nested layers, composed of combinations of metadata and raw data, with other simple or structured data. Many properties of raw data or metadata may need to be validated upon entry into the code, such as:

Implied or derived properties of data must often be calculated or inferred by the code itself. Errors in deriving properties may be considered a contributing factor to improper input validation.

Note that “input validation” has very different meanings to different people, or within different classification schemes. Caution must be used when referencing this CWE entry or mapping to it. For example, some weaknesses might involve inadvertently giving control to an attacker over an input when they should not be able to provide an input at all, but sometimes this is referred to as input validation. Finally, it is important to emphasize that the distinctions between input validation and output escaping are often blurred, and developers must be careful to understand the difference, including how input validation is not always sufficient to prevent vulnerabilities, especially when less stringent data types must be supported, such as free-form text. Consider a SQL injection scenario in which a person’s last name is inserted into a query. The name “O’Reilly” would likely pass the validation step since it is a common last name in the English language. However, this valid name cannot be directly inserted into the database because it contains the “'” apostrophe character, which would need to be escaped or otherwise transformed. In this case, removing the apostrophe might reduce the risk of SQL injection, but it would produce incorrect behavior because the wrong name would be recorded.

Potential Mitigations

  • Assume all input is malicious. Use an “accept known good” input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
  • When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, “boat” may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as “red” or “blue.”
  • Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code’s environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
  • For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
  • Even though client-side checks provide minimal benefits with respect to server-side security, they are still useful. First, they can support intrusion detection. If the server receives input that should have been rejected by the client, then it may be an indication of an attack. Second, client-side error-checking can provide helpful feedback to the user about the expectations for valid input. Third, there may be a reduction in server-side processing time for accidental input errors, although this is typically a small savings.
  • Inputs should be decoded and canonicalized to the application’s current internal representation before being validated (CWE-180, CWE-181). Make sure that your application does not inadvertently decode the same input twice (CWE-174). Such errors could be used to bypass allowlist schemes by introducing dangerous inputs after they have been checked. Use libraries such as the OWASP ESAPI Canonicalization control.
  • Consider performing repeated canonicalization until your input does not change any more. This will avoid double-decoding and similar scenarios, but it might inadvertently modify inputs that are allowed to contain properly-encoded dangerous content.