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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 "tmpnam", "tmpnam_s" or "tmpnam_r" is security-sensitive

        consistency - conventional
        security
        Security Hotspot
        • cwe
        • cert

        The functions "tmpnam", "tmpnam_s" and "tmpnam_r" are all used to return a file name that does not match an existing file, in order for the application to create a temporary file. However, even if the file did not exist at the time those functions were called, it might exist by the time the application tries to use the file name to create the files. This has been used by hackers to gain access to files that the application believed were trustworthy.

        There are alternative functions that, in addition to creating a suitable file name, create and open the file and return the file handler. Such functions are protected from this attack vector and should be preferred. About the only reason to use these functions would be to create a temporary folder, not a temporary file.

        Additionally, these functions might not be thread-safe, and if you don’t provide them buffers of sufficient size, you will have a buffer overflow.

        Ask Yourself Whether

        • There is a possibility that several threads call any of these functions simultaneously
        • There is a possibility that the resulting file is opened without forcing its creation, meaning that it might have unexpected access rights
        • The buffers passed to these functions are respectively smaller than
          • L_tmpnam for tmpnam
          • L_tmpnam_s for tmpnam_s
          • L_tmpnam for tmpnam_r

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

        Recommended Secure Coding Practices

        • Use a function that directly opens the temporary file, such a tmpfile, tmpfile_s, mkstemp or mkstemps (the last two allow more accurate control of the file name).
        • If you can’t get rid of these functions, when using the generated name to open the file, use a function that forces the creation of the file and fails if the file already exists.

        Sensitive Code Example

        int f(char *tempData) {
          char *path = tmpnam(NULL); // Sensitive
          FILE* f = fopen(tmpnam, "w");
          fputs(tempData, f);
          fclose(f);
        }
        

        Compliant Solution

        int f(char *tempData) {
          // The file will be opened in "wb+" mode, and will be automatically removed on normal program exit
          FILE* f = tmpfile(); // Compliant
          fputs(tempData, f);
          fclose(f);
        }
        

        See

        • OWASP - Top 10 2021 Category A1 - Broken Access Control
        • OWASP - Top 10 2021 Category A6 - Vulnerable and Outdated Components
        • OWASP - Top 10 2017 Category A9 - Using Components with Known Vulnerabilities
        • CWE - CWE-377 - Insecure Temporary File
        • CERT, CON33-C. - Avoid race conditions when using library functions
        • CERT, FIO21-C. - Do not create temporary files in shared directories
        • STIG Viewer - Application Security and Development: V-222567 - The application must not be vulnerable to race conditions.
        • STIG Viewer - Application Security and Development: V-222612 - The application must not be vulnerable to overflow attacks.
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