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C

C static code analysis

Unique rules to find Bugs, Vulnerabilities, Security Hotspots, and Code Smells in your C code

  • All rules 315
  • Vulnerability13
  • Bug76
  • Security Hotspot19
  • Code Smell207

  • Quick Fix 19
Filtered: 59 rules found
cwe
    Impact
      Clean code attribute
        1. Function-like macros should not be invoked without all of their arguments

           Bug
        2. Function exit paths should have appropriate return values

           Bug
        3. The number of arguments passed to a function should match the number of parameters

           Bug
        4. Non-empty statements should change control flow or have at least one side-effect

           Bug
        5. Bitwise operators should not be applied to signed operands

           Bug
        6. Limited dependence should be placed on operator precedence

           Code Smell
        7. Variables should be initialized before use

           Bug
        8. Hard-coded secrets are security-sensitive

           Security Hotspot
        9. "sprintf" should not be used

           Security Hotspot
        10. Changing working directories without verifying the success is security-sensitive

           Security Hotspot
        11. Setting capabilities is security-sensitive

           Security Hotspot
        12. Accessing files should not introduce TOCTOU vulnerabilities

           Vulnerability
        13. Account validity should be verified when authenticating users with PAM

           Vulnerability
        14. Using "tmpnam", "tmpnam_s" or "tmpnam_r" is security-sensitive

           Security Hotspot
        15. Using "strncpy" or "wcsncpy" is security-sensitive

           Security Hotspot
        16. Using "strncat" or "wcsncat" is security-sensitive

           Security Hotspot
        17. Using "strcat" or "wcscat" is security-sensitive

           Security Hotspot
        18. Using "strlen" or "wcslen" is security-sensitive

           Security Hotspot
        19. Changing directories improperly when using "chroot" is security-sensitive

           Security Hotspot
        20. Using "strcpy" or "wcscpy" is security-sensitive

           Security Hotspot
        21. "memset" should not be used to delete sensitive data

           Vulnerability
        22. POSIX functions should not be called with arguments that trigger buffer overflows

           Vulnerability
        23. Cipher algorithms should be robust

           Vulnerability
        24. Encryption algorithms should be used with secure mode and padding scheme

           Vulnerability
        25. Server hostnames should be verified during SSL/TLS connections

           Vulnerability
        26. "pthread_mutex_t" should not be locked when already locked, or unlocked when already unlocked

           Bug
        27. Using publicly writable directories is security-sensitive

           Security Hotspot
        28. Using clear-text protocols is security-sensitive

           Security Hotspot
        29. Blocking functions should not be called inside critical sections

           Code Smell
        30. Expanding archive files without controlling resource consumption is security-sensitive

           Security Hotspot
        31. Server certificates should be verified during SSL/TLS connections

           Vulnerability
        32. Using weak hashing algorithms is security-sensitive

           Security Hotspot
        33. Cryptographic keys should be robust

           Vulnerability
        34. Weak SSL/TLS protocols should not be used

           Vulnerability
        35. Dynamically allocated memory should be released

           Bug
        36. Freed memory should not be used

           Bug
        37. Memory locations should not be released more than once

           Bug
        38. Memory access should be explicitly bounded to prevent buffer overflows

           Bug
        39. Zero should not be a possible denominator

           Bug
        40. "sizeof" should not be called on pointers

           Bug
        41. XML parsers should not be vulnerable to XXE attacks

           Vulnerability
        42. Multiline blocks should be enclosed in curly braces

           Code Smell
        43. "nonnull" parameters and return values of "returns_nonnull" functions should not be null

           Bug
        44. Setting loose POSIX file permissions is security-sensitive

           Security Hotspot
        45. Conditionally executed code should be reachable

           Bug
        46. Null pointers should not be dereferenced

           Bug
        47. Using pseudorandom number generators (PRNGs) is security-sensitive

           Security Hotspot
        48. Resources should be closed

           Bug
        49. Hard-coded passwords are security-sensitive

           Security Hotspot
        50. Code annotated as deprecated should not be used

           Code Smell
        51. Unused assignments should be removed

           Code Smell
        52. All code should be reachable

           Bug
        53. "switch" statements should have "default" clauses

           Code Smell
        54. Switch cases should end with an unconditional "break" statement

           Code Smell
        55. Track uses of "TODO" tags

           Code Smell
        56. Track uses of "FIXME" tags

           Code Smell
        57. Assignments should not be made from within conditions

           Code Smell
        58. Insecure functions should not be used

           Vulnerability
        59. "scanf()" and "fscanf()" format strings should specify a field width for the "%s" string placeholder

           Vulnerability

        Using clear-text protocols is security-sensitive

        intentionality - complete
        security
        Security Hotspot
        • cwe
        • symbolic-execution

        Clear-text protocols such as ftp, telnet, or http lack encryption of transported data, as well as the capability to build an authenticated connection. It means that an attacker able to sniff traffic from the network can read, modify, or corrupt the transported content. These protocols are not secure as they expose applications to an extensive range of risks:

        • sensitive data exposure
        • traffic redirected to a malicious endpoint
        • malware-infected software update or installer
        • execution of client-side code
        • corruption of critical information

        Even in the context of isolated networks like offline environments or segmented cloud environments, the insider threat exists. Thus, attacks involving communications being sniffed or tampered with can still happen.

        For example, attackers could successfully compromise prior security layers by:

        • bypassing isolation mechanisms
        • compromising a component of the network
        • getting the credentials of an internal IAM account (either from a service account or an actual person)

        In such cases, encrypting communications would decrease the chances of attackers to successfully leak data or steal credentials from other network components. By layering various security practices (segmentation and encryption, for example), the application will follow the defense-in-depth principle.

        Note that using the http protocol is being deprecated by major web browsers.

        In the past, it has led to the following vulnerabilities:

        • CVE-2019-6169
        • CVE-2019-12327
        • CVE-2019-11065

        Ask Yourself Whether

        • Application data needs to be protected against falsifications or leaks when transiting over the network.
        • Application data transits over an untrusted network.
        • Compliance rules require the service to encrypt data in transit.
        • Your application renders web pages with a relaxed mixed content policy.
        • OS-level protections against clear-text traffic are deactivated.

        There is a risk if you answered yes to any of those questions.

        Recommended Secure Coding Practices

        • Make application data transit over a secure, authenticated and encrypted protocol like TLS or SSH. Here are a few alternatives to the most common clear-text protocols:
          • Use ssh as an alternative to telnet.
          • Use sftp, scp, or ftps instead of ftp.
          • Use https instead of http.
          • Use SMTP over SSL/TLS or SMTP with STARTTLS instead of clear-text SMTP.
        • Enable encryption of cloud components communications whenever it is possible.
        • Configure your application to block mixed content when rendering web pages.
        • If available, enforce OS-level deactivation of all clear-text traffic.

        It is recommended to secure all transport channels, even on local networks, as it can take a single non-secure connection to compromise an entire application or system.

        Sensitive Code Example

        char* http_url = "http://example.com"; // Sensitive
        char* ftp_url = "ftp://anonymous@example.com"; // Sensitive
        char* telnet_url = "telnet://anonymous@example.com"; // Sensitive
        
        #include <curl/curl.h>
        
        CURL *curl_ftp = curl_easy_init();
        curl_easy_setopt(curl_ftp, CURLOPT_URL, "ftp://example.com/"); // Sensitive
        
        CURL *curl_smtp = curl_easy_init();
        curl_easy_setopt(curl_smtp, CURLOPT_URL, "smtp://example.com:587"); // Sensitive
        

        Compliant Solution

        char* https_url = "https://example.com";
        char* sftp_url = "sftp://anonymous@example.com";
        char* ssh_url = "ssh://anonymous@example.com";
        
        #include <curl/curl.h>
        
        CURL *curl_ftps = curl_easy_init();
        curl_easy_setopt(curl_ftps, CURLOPT_URL, "ftp://example.com/");
        curl_easy_setopt(curl_ftps, CURLOPT_USE_SSL, CURLUSESSL_ALL); // FTP transport is done over TLS
        
        CURL *curl_smtp_tls = curl_easy_init();
        curl_easy_setopt(curl_smtp_tls, CURLOPT_URL, "smtp://example.com:587");
        curl_easy_setopt(curl_smtp_tls, CURLOPT_USE_SSL, CURLUSESSL_ALL); // SMTP with STARTTLS
        

        Exceptions

        No issue is reported for the following cases because they are not considered sensitive:

        • Insecure protocol scheme followed by loopback addresses like 127.0.0.1 or localhost.

        See

        Documentation

        • AWS Documentation - Listeners for your Application Load Balancers
        • AWS Documentation - Stream Encryption

        Articles & blog posts

        • Google - Moving towards more secure web
        • Mozilla - Deprecating non secure http

        Standards

        • OWASP - Top 10 2017 Category A3 - Sensitive Data Exposure
        • OWASP - Top 10 2021 Category A2 - Cryptographic Failures
        • CWE - CWE-200 - Exposure of Sensitive Information to an Unauthorized Actor
        • CWE - CWE-319 - Cleartext Transmission of Sensitive Information
        • STIG Viewer - Application Security and Development: V-222397 - The application must implement cryptographic mechanisms to protect the integrity of remote access sessions.
        • STIG Viewer - Application Security and Development: V-222534 - Service-Oriented Applications handling non-releasable data must authenticate endpoint devices via mutual SSL/TLS.
        • STIG Viewer - Application Security and Development: V-222562 - Applications used for non-local maintenance must implement cryptographic mechanisms to protect the integrity of maintenance and diagnostic communications.
        • STIG Viewer - Application Security and Development: V-222563 - Applications used for non-local maintenance must implement cryptographic mechanisms to protect the confidentiality of maintenance and diagnostic communications.
        • STIG Viewer - Application Security and Development: V-222577 - The application must not expose session IDs.
        • STIG Viewer - Application Security and Development: V-222596 - The application must protect the confidentiality and integrity of transmitted information.
        • STIG Viewer - Application Security and Development: V-222597 - The application must implement cryptographic mechanisms to prevent unauthorized disclosure of information and/or detect changes to information during transmission.
        • STIG Viewer - Application Security and Development: V-222598 - The application must maintain the confidentiality and integrity of information during preparation for transmission.
        • STIG Viewer - Application Security and Development: V-222599 - The application must maintain the confidentiality and integrity of information during reception.
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