CVE Vulnerabilities

CVE-2011-0633

Improper Input Validation

Published: May 13, 2011 | Modified: Oct 30, 2018
CVSS 3.x
N/A
Source:
NVD
CVSS 2.x
4.3 MEDIUM
AV:N/AC:M/Au:N/C:N/I:P/A:N
RedHat/V2
RedHat/V3
Ubuntu

The Net::HTTPS module in libwww-perl (LWP) before 6.00, as used in WWW::Mechanize, LWP::UserAgent, and other products, when running in environments that do not set the If-SSL-Cert-Subject header, does not enable full validation of SSL certificates by default, which allows remote attackers to spoof servers via man-in-the-middle (MITM) attacks involving hostnames that are not properly validated. NOTE: it could be argued that this is a design limitation of the Net::HTTPS API, and separate implementations should be independently assigned CVE identifiers for not working around this limitation. However, because this API was modified within LWP, a single CVE identifier has been assigned.

Weakness

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
Libwww-perl Search.cpan 5.40_01 5.40_01
Libwww-perl Search.cpan * 5.837
Libwww-perl Gisle_aas 5.828 5.828
Libwww-perl Gisle_aas 5.827 5.827
Libwww-perl Gisle_aas 5.826 5.826
Libwww-perl Gisle_aas 5.825 5.825
Libwww-perl Gisle_aas 5.811 5.811
Libwww-perl Gisle_aas 5.810 5.810
Libwww-perl Gisle_aas 5.808 5.808
Libwww-perl Gisle_aas 5.807 5.807
Libwww-perl Gisle_aas 5.74 5.74
Libwww-perl Gisle_aas 5.73 5.73
Libwww-perl Gisle_aas 5.72 5.72
Libwww-perl Gisle_aas 5.71 5.71
Libwww-perl Gisle_aas 5.53_92 5.53_92
Libwww-perl Gisle_aas 5.53_91 5.53_91
Libwww-perl Gisle_aas 5.53_90 5.53_90
Libwww-perl Gisle_aas 5.53 5.53
Libwww-perl Gisle_aas 5.52 5.52
Libwww-perl Gisle_aas 5.36 5.36
Libwww-perl Gisle_aas 5.35 5.35
Libwww-perl Gisle_aas 5.34 5.34
Libwww-perl Gisle_aas 5.33 5.33
Libwww-perl Gisle_aas 5.15 5.15
Libwww-perl Gisle_aas 5.14 5.14
Libwww-perl Gisle_aas 5.13 5.13
Libwww-perl Gisle_aas 5.12 5.12
Libwww-perl Gisle_aas 5b12 5b12
Libwww-perl Gisle_aas 5b11 5b11
Libwww-perl Gisle_aas 5b10 5b10
Libwww-perl Gisle_aas 5b9 5b9
Libwww-perl Gisle_aas 5.836 5.836
Libwww-perl Gisle_aas 5.833 5.833
Libwww-perl Gisle_aas 5.820 5.820
Libwww-perl Gisle_aas 5.819 5.819
Libwww-perl Gisle_aas 5.818 5.818
Libwww-perl Gisle_aas 5.817 5.817
Libwww-perl Gisle_aas 5.802 5.802
Libwww-perl Gisle_aas 5.801 5.801
Libwww-perl Gisle_aas 5.800 5.800
Libwww-perl Gisle_aas 5.79 5.79
Libwww-perl Gisle_aas 5.65 5.65
Libwww-perl Gisle_aas 5.64 5.64
Libwww-perl Gisle_aas 5.63 5.63
Libwww-perl Gisle_aas 5.62 5.62
Libwww-perl Gisle_aas 5.53_97 5.53_97
Libwww-perl Gisle_aas 5.47 5.47
Libwww-perl Gisle_aas 5.46 5.46
Libwww-perl Gisle_aas 5.45 5.45
Libwww-perl Gisle_aas 5.44 5.44
Libwww-perl Gisle_aas 5.20 5.20
Libwww-perl Gisle_aas 5.19 5.19
Libwww-perl Gisle_aas 5.18_05 5.18_05
Libwww-perl Gisle_aas 5.18_04 5.18_04
Libwww-perl Gisle_aas 5.07 5.07
Libwww-perl Gisle_aas 5.06 5.06
Libwww-perl Gisle_aas 5.05 5.05
Libwww-perl Gisle_aas 5.04 5.04
Libwww-perl Gisle_aas 0.04 0.04
Libwww-perl Gisle_aas 0.03 0.03
Libwww-perl Gisle_aas 0.02 0.02
Libwww-perl Gisle_aas 0.01 0.01
Libwww-perl Gisle_aas 5.831 5.831
Libwww-perl Gisle_aas 5.829 5.829
Libwww-perl Gisle_aas 5.824 5.824
Libwww-perl Gisle_aas 5.822 5.822
Libwww-perl Gisle_aas 5.815 5.815
Libwww-perl Gisle_aas 5.813 5.813
Libwww-perl Gisle_aas 5.805 5.805
Libwww-perl Gisle_aas 5.803 5.803
Libwww-perl Gisle_aas 5.78 5.78
Libwww-perl Gisle_aas 5.76 5.76
Libwww-perl Gisle_aas 5.69 5.69
Libwww-perl Gisle_aas 5.67 5.67
Libwww-perl Gisle_aas 5.60 5.60
Libwww-perl Gisle_aas 5.53_96 5.53_96
Libwww-perl Gisle_aas 5.53_94 5.53_94
Libwww-perl Gisle_aas 5.51 5.51
Libwww-perl Gisle_aas 5.49 5.49
Libwww-perl Gisle_aas 5.42 5.42
Libwww-perl Gisle_aas 5.32 5.32
Libwww-perl Gisle_aas 5.30 5.30
Libwww-perl Gisle_aas 5.21 5.21
Libwww-perl Gisle_aas 5.18_03 5.18_03
Libwww-perl Gisle_aas 5.17 5.17
Libwww-perl Gisle_aas 5.10 5.10
Libwww-perl Gisle_aas 5.08 5.08
Libwww-perl Gisle_aas 5.03 5.03
Libwww-perl Gisle_aas 5.01 5.01
Libwww-perl Gisle_aas 5b13 5b13
Libwww-perl Gisle_aas 5b8 5b8
Libwww-perl Gisle_aas 5b6 5b6
Libwww-perl Gisle_aas 5.834 5.834
Libwww-perl Gisle_aas 5.832 5.832
Libwww-perl Gisle_aas 5.830 5.830
Libwww-perl Gisle_aas 5.823 5.823
Libwww-perl Gisle_aas 5.821 5.821
Libwww-perl Gisle_aas 5.816 5.816
Libwww-perl Gisle_aas 5.814 5.814
Libwww-perl Gisle_aas 5.812 5.812
Libwww-perl Gisle_aas 5.806 5.806
Libwww-perl Gisle_aas 5.804 5.804
Libwww-perl Gisle_aas 5.77 5.77
Libwww-perl Gisle_aas 5.75 5.75
Libwww-perl Gisle_aas 5.70 5.70
Libwww-perl Gisle_aas 5.68 5.68
Libwww-perl Gisle_aas 5.66 5.66
Libwww-perl Gisle_aas 5.61 5.61
Libwww-perl Gisle_aas 5.53_95 5.53_95
Libwww-perl Gisle_aas 5.53_93 5.53_93
Libwww-perl Gisle_aas 5.50 5.50
Libwww-perl Gisle_aas 5.48 5.48
Libwww-perl Gisle_aas 5.43 5.43
Libwww-perl Gisle_aas 5.41 5.41
Libwww-perl Gisle_aas 5.31 5.31
Libwww-perl Gisle_aas 5.22 5.22
Libwww-perl Gisle_aas 5.18 5.18
Libwww-perl Gisle_aas 5.16 5.16
Libwww-perl Gisle_aas 5.11 5.11
Libwww-perl Gisle_aas 5.09 5.09
Libwww-perl Gisle_aas 5.02 5.02
Libwww-perl Gisle_aas 5.00 5.00
Libwww-perl Gisle_aas 5b7 5b7
Libwww-perl Gisle_aas 5b5 5b5

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.

References