CompTIA Updated CAS-005 Exam Questions and Answers by yunus

Analysis and Remediation Options for Each IoC:

IoC 1:

Evidence:

Source: Apache_httpd

Type: DNSQ

Dest: @10.1.1.1:53,@10.1.2.5

Data: update.s.domain, CNAME 3a129sk219r9slmfkzzz000.s.domain, 108.158.253.253

Analysis:

Analysis: The service is attempting to resolve a malicious domain.

Reason: The DNS queries and the nature of the CNAME resolution indicate that the service is trying to resolve potentially harmful domains, which is a common tactic used by malware to connect to command-and-control servers.

Remediation:

Remediation: Implement a blocklist for known malicious ports.

Reason: Blocking known malicious domains at the DNS level prevents the resolution of harmful domains, thereby protecting the network from potential connections to malicious servers.

IoC 2:

Evidence:

Src: 10.0.5.5

Dst: 10.1.2.1, 10.1.2.2, 10.1.2.3, 10.1.2.4, 10.1.2.5

Proto: IP_ICMP

Data: ECHO

Action: Drop

Analysis:

Analysis: Someone is footprinting a network subnet.

Reason: The repeated ICMP ECHO requests to different addresses within a subnet indicate that someone is scanning the network to discover active hosts, a common reconnaissance technique used by attackers.

Remediation:

Remediation: Block ping requests across the WAN interface.

Reason: Blocking ICMP ECHO requests on the WAN interface can prevent attackers from using ping sweeps to gather information about the network topology and active devices.

IoC 3:

Evidence:

Proxylog:

GET /announce?info_hash=%01dff%27f%21%10%c5%wp%4e%1d%6f%63%3c%49%6d & peer_id%3dxJFS

Uploaded=0 & downloaded=0 & left=3767869 & compact=1 & ip=10.5.1.26 & event=started

User-Agent: RAZA 2.1.0.0

Host: localhost

Connection: Keep-Alive

HTTP200 OK

Analysis:

Analysis: An employee is using P2P services to download files.

Reason: The HTTP GET request with parameters related to a BitTorrent client indicates that the employee is using peer-to-peer (P2P) services, which can lead to unauthorized data transfer and potential security risks.

Remediation:

Remediation: Enforce endpoint controls on third-party software installations.

Reason: By enforcing strict endpoint controls, you can prevent the installation and use of unauthorized software, such as P2P clients, thereby mitigating the risk of data leaks and other security threats associated with such applications.

The situation where several employees were contacted by the same individual impersonating a recruiter best describes aspear-phishing campaign. Here’s why:

Targeted Approach: Spear-phishing involves targeting specific individuals within an organization with personalized and convincing messages to trick them into divulging sensitive information or performing actions that compromise security.

Impersonation: The use of impersonation, in this case, a recruiter, is a common tactic in spear-phishing to gain the trust of the targeted individuals and increase the likelihood of a successful attack.

Correlated Contacts: The fact that several employees were contacted by the same individual suggests a coordinated effort to breach the organization’s security by targeting multiple points of entry through social engineering.

On-path decryption attacks, such as BEAST (Browser Exploit Against SSL/TLS) and other related vulnerabilities, often exploit weaknesses in the implementation of CBC (Cipher Block Chaining) mode. To mitigate these attacks, the following actions are recommended:

B. Removing support for CBC-based key exchange and signing algorithms: CBC mode is vulnerable to certain attacks like BEAST. By removing support for CBC-based ciphers, you can eliminate one of the primary vectors for these attacks. Instead, use modern cipher modes like GCM (Galois/Counter Mode) which offer better security properties.

C. Adding TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA256: This cipher suite uses Elliptic Curve Diffie-Hellman Ephemeral (ECDHE) for key exchange, which provides perfect forward secrecy. It also uses AES in GCM mode, which is not susceptible to the same attacks as CBC. SHA-256 is a strong hash function that ensures data integrity.