What is RCE ?
Remote code execution is the ability an attacker has to access someone else's computing device and make changes, no matter where the device is geographically located.
When user input is added to a file or string and the entire package is executed on the programming language's parser, remote code execution is utilized to disclose a type of vulnerability that can be exploited.
An extensive attack that would compromise the web server and the entire web application can start with a remote code execution attack.
RCE may potentially result in network pivoting, persistence establishment, and privilege escalation. Because of this, the severity of RCE is always HIGH or CRITICAL. Additionally, you should be aware that almost all programming languages provide various code evaluation functions.
Allowing user inputs to access functions that are evaluating code in the same programming language may also result in a code evaluation.
Because the user-controlled input was created by the developer to be inside any of these routines, this form of measure may have been developed on purpose to obtain access to the mathematical functions of the programming language or accidentally.
The implementation of this course of action is not advised. Even using code assessment is viewed negatively by many individuals.
How RCE works ?
There are different ways of performing a remote code execution because it can target different layers of a server.
Injecting code and taking over the instruction pointer are two common ways to carry out an RCE.
This makes it possible for an attacker to direct someone to carry out the next command or operation.
Code can be injected in a variety of places and ways, but once this is the case, attackers must "point" at the injected code for it to be executed.
The actual code itself could take the shape of a script, command, or another item.
Types of RCE Attack
- By embedding code in an object that is allocated with one pointer but read with another, attackers take advantage of this vulnerability. As a result, the second pointer causes the code to be injected.
- Attackers can design an object that, if deserialized, can execute dynamic code by formatting user input in a specific way.
Buffer overflow and buffer over-read
Buffer overflow is also known as out-of-bounds write and buffer overrun. Together with buffer over-read, it refers to memory safety vulnerabilities related to the memory partition known as a buffer
An attacker will use poor memory allocation in a buffer overflow since, for instance, bounds-checking safeguards aren't there. When this happens, data may be written outside the buffer's boundaries, overwriting memory in nearby buffer partitions.
Such overwriting can damage or destroy important data, cause a crash, or lead to an RCE triggered through the use of an instruction pointer security vulnerability.
Impacts of RCE ?
Access to an application or server
Access to data
Denial of service
Ransomware and cryptomining
Famous RCE Attacks
The DoublePulsar programme was used by the WannaCry ransomware cryptoworm attack to install and run itself. It did this by utilising the RCE exploit known as EternalBlue.
Systems running Windows were the target of the assault. As soon as the worm is installed, it encrypts data and demands a ransom.
EternalBlue targeted a security vulnerability in Microsoft’s Server Message Block (SMB) protocol. This vulnerability allowed attackers to inject and remotely execute code.
Millions of devices worldwide are thought to be at risk from the remote code execution vulnerability known as Log4Shell in the popular Java logging framework Log4j.
The phrase "single biggest, most serious vulnerability ever" has been used. Although it had been around since 2013, it was only discovered in November 2021 and made public in December of the same year.
The vulnerability allows users to execute arbitrary Java code on servers, opening the door for crypto mining, creating botnets, and injecting ransomware.
Ways to Prevent RCE?
Regular security updates
Input sanitation and access control
Memory management .
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