AskSia

Plus

请你解决一下这道题，并解释一下 a) Static Analysis (7 points) The code below shows an excerpt of...

Jul 29, 2024

请你解决一下这道题，并解释一下

Explanation

This problem involves performing a taint analysis on a given inter-procedural control flow graph of a malicious Android application. The goal is to track the flow of sensitive data (deviceId) through the program to identify if it reaches a sink (sendTextMessage) without proper sanitization.

Step-by-step Instruction

▪

Initialize the taint set: Start with an empty taint set

▪

Track the flow of tainted data: Follow the control flow graph and apply the taint propagation rules to track the flow of the deviceId

▪

Analyze assignment statements: For each assignment statement, check if the right-hand side is tainted and propagate the taint to the left-hand side

▪

Analyze method calls: For each method call, check if any of the arguments are tainted and propagate the taint to the corresponding parameters in the callee

▪

Merge taint sets: When control flow paths merge, compute the union of the taint sets from each path

▪

Check for tainted sinks: At the end of the analysis, check if any tainted data reaches the sink (`sendTextMessage`)

Time Complexity

The time complexity is O(n), where n is the number of statements in the control flow graph.

Space Complexity

The space complexity is O(m), where m is the number of variables and fields that can be tainted.

Let's break down the taint analysis for the given code: 1. Identify the source and sink: - Source: "telephonyManager.getDeviceId()" - Sink: "sms.sendTextMessage()" 2. Initialize the taint set: - Taint set: {} 3. Track the flow of tainted data: - Line 8: "doRandomTest(telephonyManager.getDeviceId())" - "id" is tainted because "getDeviceId()" is a source. - Taint set: {id} - Line 26: "f1.a1 = id" - "f1.a1" is tainted because "id" is tainted. - Taint set: {id, f1.a1} - Line 37: "bar.a2 = foo" - "bar.a2" is tainted if "foo" is tainted. - Taint set: {id, f1.a1, bar.a2} - Line 39: "sms.sendTextMessage("+4988", null, b1.a2.a1, null, null)" - "b1.a2.a1" is tainted if "b1.a2" is tainted. - Since "bar.a2" is tainted and "bar" is assigned to "b1", "b1.a2" is tainted. - Therefore, "b1.a2.a1" is tainted. 4. Check for tainted sinks: - The sink "sendTextMessage" is reached with tainted data "b1.a2.a1".

Explanation

The taint analysis shows that the deviceId is indeed leaked through the SMS without the user's knowledge.

解决一下这道题呢

解决这道题需要使用Common Vulnerability Scoring System (CVSS)来评估漏洞。以下是每个指标的评分和解释：

Vulnerability Assessment

▪

Attack Vector: Local : 由于漏洞是通过具有删除权限的用户在本地系统上操作的，因此攻击向量为本地。

▪

Attack Complexity: Low : 攻击复杂度低，因为攻击者只需要删除权限即可执行攻击。

▪

Privileges Required: Low : 攻击者需要低权限（删除权限）来执行攻击。

▪

User Interaction: None : 不需要用户交互，攻击者可以直接执行删除操作。

▪

Scope: Changed : 攻击影响范围改变，因为攻击者可以删除其他用户的词汇表条目。

▪

Confidentiality: Low : 机密性影响较低，因为删除词汇表条目不会直接泄露敏感信息。

▪

Integrity: High : 完整性影响高，因为删除词汇表条目会导致数据丢失。

▪

Availability: Low : 可用性影响较低，因为删除词汇表条目不会导致系统不可用。

以上是对漏洞的评估和解释。

解决一下这道问题呢？

Step-by-step Instruction

▪

Analyze each function for potential coding mistakes: Look for issues such as improper resource handling, concurrency issues, and security vulnerabilities

▪

Document each identified mistake with its line number and a brief explanation: This will help in understanding the specific issues in the code

Explanation

The code contains several mistakes that violate secure coding principles. Below are the identified mistakes along with their explanations.

1. Line 6-9:

java

Explanation

The "id" variable is not thread-safe. Multiple threads accessing this method can lead to race conditions.

2. Line 11:

java

Explanation

The method does not have a return type. It should be "public void setConnection(Connection conn)".

3. Line 17-18:

java

Explanation

Hardcoding the database URL is a security risk. It should be externalized to a configuration file.

4. Line 19:

java

Explanation

The "conn" variable is not defined in this scope. It should be "this.connection.prepareStatement()".

5. Line 25:

java

Explanation

Closing the connection in the "finally" block without checking if it is null can lead to a "NullPointerException".

Time Complexity

The time complexity of the code is generally O(1) for each method, except for the database operations which depend on the database's performance.

Space Complexity

The space complexity is O(1) as the code does not use any additional data structures that grow with input size.

解决一下这张图片上的两个问题呢

Step-by-step Instruction

▪

Analyze the code: Carefully read the provided Java code to spot the vulnerabilities

▪

Explain the vulnerabilities: Provide a detailed explanation of why the identified lines are insecure

▪

Identify the lines causing the vulnerabilities: Pinpoint the exact lines in the code that are problematic

▪

Explain the defensive coding principle: Describe the principle that is violated and how it mitigates the vulnerability

Question i) Name the kind of vulnerability and explain why it is insecure.

Explanation

The first vulnerability is using a "String" for the password. Strings are immutable in Java, meaning once created, they cannot be modified. This can lead to security issues because the password remains in memory until garbage collection occurs, which can be a potential target for memory dump attacks.

Question ii) Identify the line(s) that cause the vulnerability and describe the problem.

Explanation

The second vulnerability is in the line where the password is converted to a "char[]" array. Specifically, the line "password.getChars(0, 32, chars, 0);" (line 11). This line is problematic because it assumes the password is at least 32 characters long. If the password is shorter, it will throw an "IndexOutOfBoundsException".

Question iii) Explain which defensive coding principle is violated and how it mitigates the vulnerability.

Explanation

The defensive coding principle violated here is "Fail-Safe Defaults". The code should not assume the password length and should handle cases where the password is shorter than expected. This can be mitigated by checking the length of the password before attempting to copy it into the "char[]" array.

Example of Corrected Code

java

Time Complexity

The time complexity of the "verifyPassword" method is O(n), where n is the length of the password. This is because the method performs operations that depend on the length of the password, such as copying characters and hashing.

Space Complexity

The space complexity is O(1) for the fixed-size arrays and O(n) for the password length. The method uses a fixed amount of space for the "char[]" and "byte[]" arrays, but the space required for the password depends on its length.

解释一下图片中的3个问题

解释一下图片中的3个问题

Compression and Encryption

▪

Approach 1: Compress-then-Encrypt : This approach involves compressing the data first and then encrypting it. The main issue is that if the compression algorithm has vulnerabilities, it could potentially be exploited to reveal information about the original data. However, this approach is generally considered more secure because encryption hides the data patterns that could be exploited

▪

Approach 2: Encrypt-then-Compress : This approach involves encrypting the data first and then compressing it. The main issue is that encrypted data is usually not compressible, which makes this approach inefficient. Additionally, if the encryption is weak, the compression step could reveal patterns in the data that could be exploited

▪

Recommendation: Encrypt-then-Compress should never be used because it is inefficient and could potentially reveal patterns in the data

The combination of compression and encryption should use the Compress-then-Encrypt approach.

Digital Signatures

▪

Definition: Digital Signatures are cryptographic techniques used to verify the authenticity and integrity of a message, software, or digital document

▪

How They Work: A digital signature is created by generating a hash of the message and then encrypting the hash with the sender's private key. The recipient can verify the signature by decrypting the hash with the sender's public key and comparing it to a hash they generate from the received message

▪

Properties Gained: :

▪ ⋮ Authenticity: Ensures that the message was sent by the claimed sender.

‖ ▪

Integrity: Ensures that the message has not been altered

▪

Non-repudiation: Ensures that the sender cannot deny sending the message

Digital Signatures provide authenticity, integrity, and non-repudiation.

Hash Functions

▪

Claim Assessment: The claim that with unlimited time and computational power, one can compute the original value for a given hash value and hash function is theoretically correct but practically infeasible

▪

Justification: :

▪ ⋮ Pre-image Resistance: Good hash functions are designed to make it computationally infeasible to find the original input from its hash value.

‖ ▪

Computational Limits: Even with unlimited time and computational power, the sheer number of possible inputs makes it impractical to reverse-engineer the original value

The claim is theoretically correct but practically infeasible due to the properties of good hash functions and computational limits.