diff --git a/flawfinder b/flawfinder index d5c0aa2..5957afe 100755 --- a/flawfinder +++ b/flawfinder @@ -846,10 +846,27 @@ def cpp_unsafe_stl(hit): if len(hit.parameters) <= 4: add_warning(hit) +safe_load_library_flags = [ + # Load only from the folder where the .exe file is located + 'LOAD_LIBRARY_SEARCH_APPLICATION_DIR', + # Combination of application, System32 and user directories + 'LOAD_LIBRARY_SEARCH_DEFAULT_DIRS', + # This flag requires an absolute path to the DLL to be passed + 'LOAD_LIBRARY_SEARCH_DLL_LOAD_DIR', + # Load only from System32 + 'LOAD_LIBRARY_SEARCH_SYSTEM32', + # Load only from directories specified with AddDllDirectory + # or SetDllDirectory + 'LOAD_LIBRARY_SEARCH_USER_DIRS', + # Loading from the current directory will only proceed if + # the current directory is part of the safe load list + 'LOAD_LIBRARY_SAFE_CURRENT_DIRS' +] + def load_library_ex(hit): - # If parameter 3 is 'LOAD_LIBRARY_SEARCH_SYSTEM32', it's safe. + # If parameter 3 has one of the flags below, it's safe. if (len(hit.parameters) >= 4 and - hit.parameters[3] == 'LOAD_LIBRARY_SEARCH_SYSTEM32'): + any(flag in hit.parameters[3] for flag in safe_load_library_flags)): return normal(hit) @@ -1298,12 +1315,12 @@ c_ruleset = { "LoadLibrary": (normal, 3, "Ensure that the full path to the library is specified, or current directory may be used (CWE-829, CWE-20)", - "Use registry entry or GetWindowsDirectory to find library path, if you aren't already", + "Use LoadLibraryEx with one of the search flags, or call SetSearchPathMode to use a safe search path, or pass a full path to the library", "misc", "", {'input': 1}), "LoadLibraryEx": (load_library_ex, 3, "Ensure that the full path to the library is specified, or current directory may be used (CWE-829, CWE-20)", - "Use registry entry or GetWindowsDirectory to find library path, if you aren't already", + "Use a flag like LOAD_LIBRARY_SEARCH_SYSTEM32 or LOAD_LIBRARY_SEARCH_APPLICATION_DIR to search only desired folders", "misc", "", {'input': 1}), "SetSecurityDescriptorDacl": diff --git a/test/correct-results-008.txt b/test/correct-results-008.txt index dfcc58d..be8316e 100644 --- a/test/correct-results-008.txt +++ b/test/correct-results-008.txt @@ -5,8 +5,8 @@ Number of rules (primarily dangerous function names) in C/C++ ruleset: 222 ANALYSIS SUMMARY: No hits found. -Lines analyzed = 123 -Physical Source Lines of Code (SLOC) = 85 +Lines analyzed = 125 +Physical Source Lines of Code (SLOC) = 86 Hits@level = [0] 0 [1] 0 [2] 0 [3] 0 [4] 0 [5] 0 Hits@level+ = [0+] 0 [1+] 0 [2+] 0 [3+] 0 [4+] 0 [5+] 0 Hits/KSLOC@level+ = [0+] 0 [1+] 0 [2+] 0 [3+] 0 [4+] 0 [5+] 0 diff --git a/test/correct-results.csv b/test/correct-results.csv index 2b556e2..7770622 100644 --- a/test/correct-results.csv +++ b/test/correct-results.csv @@ -18,7 +18,8 @@ test.c,49,3,4,buffer,_mbscpy,Does not check for buffer overflows when copying to test.c,56,3,4,buffer,lstrcat,Does not check for buffer overflows when concatenating to destination [MS-banned] (CWE-120),,,CWE-120," lstrcat(d,s);",364b4c512862fdccbca27d2fa7737995b5d24b637a760976c940ae636218d340 test.c,79,3,3,shell,CreateProcess,This causes a new process to execute and is difficult to use safely (CWE-78),"Specify the application path in the first argument, NOT as part of the second, or embedded spaces could allow an attacker to force a different program to run",,CWE-78," CreateProcess(NULL, ""C:\\Program Files\\GoodGuy\\GoodGuy.exe -x"", """");",3c712b38d0857bde3832d85ad35ac9859be55c5f5f1c20af659a577dd4d0acbf test.c,79,3,3,shell,CreateProcess,This causes a new process to execute and is difficult to use safely (CWE-78),"Specify the application path in the first argument, NOT as part of the second, or embedded spaces could allow an attacker to force a different program to run",,CWE-78," CreateProcess(NULL, ""C:\\Program Files\\GoodGuy\\GoodGuy.exe -x"", """");",3c712b38d0857bde3832d85ad35ac9859be55c5f5f1c20af659a577dd4d0acbf -test.c,97,20,3,buffer,getopt_long,"Some older implementations do not protect against internal buffer overflows (CWE-120, CWE-20)","Check implementation on installation, or limit the size of all string inputs",,"CWE-120, CWE-20"," while ((optc = getopt_long (argc, argv, ""a"",longopts, NULL )) != EOF) {",5bedf6e5bccf596008ef191ec4c5d4cc51a32cff0c05ef62d5f10fab93d0cc24 +test.c,81,10,3,misc,LoadLibraryEx,"Ensure that the full path to the library is specified, or current directory may be used (CWE-829, CWE-20)",Use a flag like LOAD_LIBRARY_SEARCH_SYSTEM32 or LOAD_LIBRARY_SEARCH_APPLICATION_DIR to search only desired folders,,"CWE-829, CWE-20"," (void) LoadLibraryEx(L""user32.dll"", nullptr, LOAD_LIBRARY_AS_DATAFILE);",b1f99ecaa31e682487d795afbf03282fd56ad9f2aa630d0196219b277d2a68c9 +test.c,99,20,3,buffer,getopt_long,"Some older implementations do not protect against internal buffer overflows (CWE-120, CWE-20)","Check implementation on installation, or limit the size of all string inputs",,"CWE-120, CWE-20"," while ((optc = getopt_long (argc, argv, ""a"",longopts, NULL )) != EOF) {",5bedf6e5bccf596008ef191ec4c5d4cc51a32cff0c05ef62d5f10fab93d0cc24 test.c,16,2,2,buffer,strcpy,Does not check for buffer overflows when copying to destination [MS-banned] (CWE-120),"Consider using snprintf, strcpy_s, or strlcpy (warning: strncpy easily misused)",Risk is low because the source is a constant string.,CWE-120," strcpy(a, gettext(""Hello there"")); // Did this work?",d64070fb93ff0bb797fb926f4dddc7212d42f77e288d5ceb0cd30ed2979fa28d test.c,19,2,2,buffer,sprintf,Does not check for buffer overflows (CWE-120),"Use sprintf_s, snprintf, or vsnprintf",Risk is low because the source has a constant maximum length.,CWE-120," sprintf(s, ""hello"");",907b46be1c3ea7b38f90a4d1b0f43b7751cd8cbe38fae840930ff006b702157d test.c,45,3,2,buffer,char,"Statically-sized arrays can be improperly restricted, leading to potential overflows or other issues (CWE-119!/CWE-120)","Perform bounds checking, use functions that limit length, or ensure that the size is larger than the maximum possible length",,CWE-119!/CWE-120, char d[20];,36c87517700337a59cc3ad3218cfdde56cad37d69cdeccee5a55ab232d5c7946 @@ -27,7 +28,7 @@ test.c,50,3,2,buffer,memcpy,Does not check for buffer overflows when copying to test.c,53,3,2,buffer,memcpy,Does not check for buffer overflows when copying to destination (CWE-120),Make sure destination can always hold the source data,,CWE-120," memcpy(&n,s,sizeof(s)); // fail - sizeof not of destination",01bcc2c8ba2d928ac3315b4dcc6593042ea05e62888a10a6d2cf16797a65ed32 test.c,54,3,2,buffer,memcpy,Does not check for buffer overflows when copying to destination (CWE-120),Make sure destination can always hold the source data,,CWE-120," memcpy(d,s,n); // fail - size unguessable",2517a2fb5981193a6017cca660d16e85aab133706cbec302df97aaa623fc77ef test.c,55,3,2,buffer,CopyMemory,Does not check for buffer overflows when copying to destination (CWE-120),Make sure destination can always hold the source data,,CWE-120," CopyMemory(d,s);",977f8c805ddd76ff32e0f7aea08701ba97d9ce6955136e98b308ed4f70eb2e11 -test.c,103,7,2,misc,fopen,"Check when opening files - can an attacker redirect it (via symlinks), force the opening of special file type (e.g., device files), move things around to create a race condition, control its ancestors, or change its contents? (CWE-362)",,,CWE-362," f = fopen(""/etc/passwd"", ""r""); ",2ec6928c77a8b54caa61d0459f367c4394ee1f5e6f488753f587bfa9c780bad8 +test.c,105,7,2,misc,fopen,"Check when opening files - can an attacker redirect it (via symlinks), force the opening of special file type (e.g., device files), move things around to create a race condition, control its ancestors, or change its contents? (CWE-362)",,,CWE-362," f = fopen(""/etc/passwd"", ""r""); ",2ec6928c77a8b54caa61d0459f367c4394ee1f5e6f488753f587bfa9c780bad8 test.c,15,2,1,buffer,strcpy,Does not check for buffer overflows when copying to destination [MS-banned] (CWE-120),"Consider using snprintf, strcpy_s, or strlcpy (warning: strncpy easily misused)",Risk is low because the source is a constant character.,CWE-120," strcpy(a, ""\n""); // Did this work?",0badc5f4c500d17b42794feaca54ee0f49e607a32510af3ed749579001017edb test.c,18,2,1,buffer,sprintf,Does not check for buffer overflows (CWE-120),"Use sprintf_s, snprintf, or vsnprintf",Risk is low because the source is a constant character.,CWE-120," sprintf(s, ""\n"");",c65fbd60851f3c8ace22332805966606488c0d242c1823493c582e267609b1a7 test.c,26,2,1,buffer,scanf,It's unclear if the %s limit in the format string is small enough (CWE-120),"Check that the limit is sufficiently small, or use a different input function",,CWE-120," scanf(""%10s"", s);",e24c4c801f10acfa93098b2bef58524efe4f88237f2dd8b58be9afa838616afe diff --git a/test/correct-results.html b/test/correct-results.html index 1d8a712..5b53939 100644 --- a/test/correct-results.html +++ b/test/correct-results.html @@ -171,7 +171,17 @@ Examining test2.c 
   CreateProcess(NULL, "C:\\Program Files\\GoodGuy\\GoodGuy.exe -x", "");
-
  • test.c:97: [3] (buffer) getopt_long: +
  • test.c:81: [3] (misc) LoadLibraryEx: + Ensure that the full path to the library is specified, or current directory + may be used (CWE-829, CWE-20). Use a + flag like LOAD_LIBRARY_SEARCH_SYSTEM32 or + LOAD_LIBRARY_SEARCH_APPLICATION_DIR to search only desired folders. +
    +  (void) LoadLibraryEx(L"user32.dll", nullptr, LOAD_LIBRARY_AS_DATAFILE);
+
    +
  • test.c:99: [3] (buffer) getopt_long: Some older implementations do not protect against internal buffer overflows (CWE-120, CWE-20). Check @@ -243,7 +253,7 @@ Examining test2.c 
       CopyMemory(d,s);
    -
  • test.c:103: [2] (misc) fopen: +
  • test.c:105: [2] (misc) fopen: Check when opening files - can an attacker redirect it (via symlinks), force the opening of special file type (e.g., device files), move things around to create a race condition, control its ancestors, or change its @@ -321,15 +331,15 @@ Examining test2.c

    Analysis Summary

    -Hits = 38 +Hits = 39
    -Lines analyzed = 124 +Lines analyzed = 126
    -Physical Source Lines of Code (SLOC) = 85 +Physical Source Lines of Code (SLOC) = 86
    -Hits@level = [0] 16 [1] 9 [2] 9 [3] 3 [4] 10 [5] 7
    -Hits@level+ = [0+] 54 [1+] 38 [2+] 29 [3+] 20 [4+] 17 [5+] 7
    -Hits/KSLOC@level+ = [0+] 635.294 [1+] 447.059 [2+] 341.176 [3+] 235.294 [4+] 200 [5+] 82.3529
    +Hits@level = [0] 16 [1] 9 [2] 9 [3] 4 [4] 10 [5] 7
    +Hits@level+ = [0+] 55 [1+] 39 [2+] 30 [3+] 21 [4+] 17 [5+] 7
    +Hits/KSLOC@level+ = [0+] 639.535 [1+] 453.488 [2+] 348.837 [3+] 244.186 [4+] 197.674 [5+] 81.3953
    Suppressed hits = 2 (use --neverignore to show them)
    Minimum risk level = 1 diff --git a/test/correct-results.txt b/test/correct-results.txt index 6f726f3..84e1963 100644 --- a/test/correct-results.txt +++ b/test/correct-results.txt @@ -75,7 +75,11 @@ test.c:79: [3] (shell) CreateProcess: (CWE-78). Specify the application path in the first argument, NOT as part of the second, or embedded spaces could allow an attacker to force a different program to run. -test.c:97: [3] (buffer) getopt_long: +test.c:81: [3] (misc) LoadLibraryEx: + Ensure that the full path to the library is specified, or current directory + may be used (CWE-829, CWE-20). Use a flag like LOAD_LIBRARY_SEARCH_SYSTEM32 + or LOAD_LIBRARY_SEARCH_APPLICATION_DIR to search only desired folders. +test.c:99: [3] (buffer) getopt_long: Some older implementations do not protect against internal buffer overflows (CWE-120, CWE-20). Check implementation on installation, or limit the size of all string inputs. @@ -108,7 +112,7 @@ test.c:54: [2] (buffer) memcpy: test.c:55: [2] (buffer) CopyMemory: Does not check for buffer overflows when copying to destination (CWE-120). Make sure destination can always hold the source data. -test.c:103: [2] (misc) fopen: +test.c:105: [2] (misc) fopen: Check when opening files - can an attacker redirect it (via symlinks), force the opening of special file type (e.g., device files), move things around to create a race condition, control its ancestors, or change its @@ -146,12 +150,12 @@ test.c:70: [1] (buffer) MultiByteToWideChar: ANALYSIS SUMMARY: -Hits = 38 -Lines analyzed = 124 -Physical Source Lines of Code (SLOC) = 85 -Hits@level = [0] 16 [1] 9 [2] 9 [3] 3 [4] 10 [5] 7 -Hits@level+ = [0+] 54 [1+] 38 [2+] 29 [3+] 20 [4+] 17 [5+] 7 -Hits/KSLOC@level+ = [0+] 635.294 [1+] 447.059 [2+] 341.176 [3+] 235.294 [4+] 200 [5+] 82.3529 +Hits = 39 +Lines analyzed = 126 +Physical Source Lines of Code (SLOC) = 86 +Hits@level = [0] 16 [1] 9 [2] 9 [3] 4 [4] 10 [5] 7 +Hits@level+ = [0+] 55 [1+] 39 [2+] 30 [3+] 21 [4+] 17 [5+] 7 +Hits/KSLOC@level+ = [0+] 639.535 [1+] 453.488 [2+] 348.837 [3+] 244.186 [4+] 197.674 [5+] 81.3953 Suppressed hits = 2 (use --neverignore to show them) Minimum risk level = 1 diff --git a/test/test.c b/test/test.c index 5405624..10adc64 100644 --- a/test/test.c +++ b/test/test.c @@ -77,8 +77,10 @@ demo2() { SetSecurityDescriptorDacl(&sd,TRUE,NULL,FALSE); /* This one is a bad idea - first param shouldn't be NULL */ CreateProcess(NULL, "C:\\Program Files\\GoodGuy\\GoodGuy.exe -x", ""); - /* This should be ignored */ - (void) LoadLibraryEx(L"user32.dll", nullptr, LOAD_LIBRARY_SEARCH_SYSTEM32); + /* Bad, may load from current directory */ + (void) LoadLibraryEx(L"user32.dll", nullptr, LOAD_LIBRARY_AS_DATAFILE); + /* This should be ignored, since it's loading only from System32 */ + (void) LoadLibraryEx(L"user32.dll", nullptr, LOAD_LIBRARY_SEARCH_SYSTEM32 | LOAD_LIBRARY_REQUIRE_SIGNED_TARGET); /* Test interaction of quote characters */ printf("%c\n", 'x'); printf("%c\n", '"');