TCP ports 139 and 445 are associated with Windows file and printer sharing. Port 139 supports SMB over the legacy NetBIOS Session Service, while port 445 carries SMB directly over TCP. If these services are reachable from untrusted or external segments, attackers may attempt share enumeration, account discovery, relay attacks, password guessing, or exploitation of SMB vulnerabilities.
The required countermeasure is to block or tightly restrict these ports at firewalls and segmentation boundaries. Option A uses the word "disable," but its security intent is correct: systems outside approved management or file-sharing zones should not be able to communicate directly with TCP 139 or 445.
Microsoft's SMB traffic guidance recommends restricting SMB traffic and blocking unnecessary inbound and outbound access, particularly at perimeter boundaries.
Changing community strings applies to SNMP enumeration, which commonly involves UDP ports 161 and
162. Blocking port 2049 protects NFS rather than Windows SMB or NetBIOS file sharing. SSL or STARTTLS may protect supported application traffic from interception, but it does not remove the externally exposed enumeration surface and is not the standard control for legacy SMB exposure. Therefore, restricting TCP 139 and 445 is the most directly effective countermeasure.

The issue described is excessive or inappropriate application permission granting in a BYOD environment.
Employees install apps that request access to sensitive device resources-contacts, camera, messaging- despite those permissions not being necessary for the app's stated purpose. This creates a risk of data harvesting and corporate information leakage if a malicious or overly intrusive app is installed. The most direct guideline to prevent this behavior is to review the permissions requested by apps before installing them.
Mobile operating systems rely heavily on permission models to control access to sensitive data and device capabilities. When users approve broad permissions without scrutiny, they effectively authorize the app to collect and transmit sensitive information. Enforcing a culture and policy of checking permissions (and denying or uninstalling apps that request unnecessary access) directly addresses the root cause in the scenario:
user consent enabling excessive privilege at the app level. In a corporate BYOD program, this guideline is often paired with mobile security controls such as enterprise app stores, allowlists/denylists, MDM/MAM policies, and user awareness training, but the question asks for the most direct preventive guideline.
Why the other options are less direct:
Encryption at rest (A) helps protect stored data if the device is lost or compromised, but it does not stop an authorized app from accessing data via granted permissions.
Automatic locking/biometrics (B) reduces unauthorized physical access, but it does not constrain what a permitted app can access while the device is in use.
App passwords (D) can help restrict casual access to an app, but they do not solve the problem of an app legitimately being granted invasive permissions.
Therefore, the best answer is C. Review permissions requested by apps before installing them.

An untethered jailbreak is one that allows a telephone to finish a boot cycle when being pwned with none interruption to jailbreak-oriented practicality.
Untethered jailbreaks area unit the foremost sought-after of all, however they're additionally the foremost difficult to attain due to the powerful exploits and organic process talent they need. associate unbound jailbreak is sent over a physical USB cable association to a laptop or directly on the device itself by approach of associate application-based exploit, like a web site in campaign.
Upon running associate unbound jailbreak, you'll be able to flip your pwned telephone off and on once more while not running the jailbreak tool once more. all of your jailbreak tweaks and apps would then continue in operation with none user intervention necessary.
It's been an extended time since IOS has gotten the unbound jailbreak treatment. the foremost recent example was the computer-based Pangu break, that supported most handsets that ran IOS nine.1. We've additionally witnessed associate unbound jailbreak within the kind of JailbreakMe, that allowed users to pwn their handsets directly from the mobile campaign applications programme while not a laptop.

The attacker is exploiting side-channel information by observing hardware characteristics such as power consumption and timing variations during cryptographic operations. These physical signals can leak information about secret keys, enabling their deduction without breaking the cryptographic algorithm itself.