CVE-2024-21652

Summary

An attacker can effectively bypass the rate limit and brute force protections by exploiting the application's weak cache-based mechanism. This loophole in security can be combined with other vulnerabilities to attack the default admin account. This flaw undermines a previously patched CVE intended to protect against brute-force attacks.

Details

The application's brute force protection relies on a cache mechanism that tracks login attempts for each user. This cache is limited to a defaultMaxCacheSize of 1000 entries. An attacker can overflow this cache by bombarding it with login attempts for different users, thereby pushing out the admin account's failed attempts and effectively resetting the rate limit for that account.

The brute force protection mechanism's code:

   if failed && len(failures) >= getMaximumCacheSize() {
       log.Warnf("Session cache size exceeds %d entries, removing random entry",

getMaximumCacheSize())
       idx := rand.Intn(len(failures) - 1)
       var rmUser string
       i := 0
       for key := range failures {

           if i == idx {
               rmUser = key

               delete(failures, key)

break

}

i++ }

       log.Infof("Deleted entry for user %s from cache", rmUser)
   }

PoC

1. Set up the application environment and identify the login page.
2. Execute 4 failed login attempts for the admin account.
3. Run a Burp Intruder attack to populate the cache with login attempts for usernames ranging from 1 to 10000.
4. After 1000 attempts, start monitoring to see if the admin entries in the cache have been cleared.
5. At this point, brute-force the admin account.

In just 15 minutes, the PoC was able to perform 230 brute force attempts on the admin account. This rate allows for approximately 1000 requests per hour, effectively rendering the older CVE rate limit patches useless.

Impact

This is a severe vulnerability that enables attackers to perform brute force attacks at an accelerated rate, especially targeting the default admin account.

Summary

An attacker can exploit a chain of vulnerabilities, including a Denial of Service (DoS) flaw and in-memory data storage weakness, to effectively bypass the application's brute force login protection. This makes the application susceptible to brute force attacks, compromising the security of all user accounts.

Details

The issue arises from two main vulnerabilities:

1. The application crashes due to a previously described DoS vulnerability caused by unsafe array modifications in a multi-threaded environment.
2. The application saves the data of failed login attempts in-memory, without persistent storage. When the application crashes and restarts, this data is lost, resetting the brute force protections.

// LoginAttempts is a timestamped counter for failed login attempts

type LoginAttempts struct {  
// Time of the last failed login LastFailed time.Time `json:"lastFailed"` // Number of consecutive login failures FailCount int `json:"failCount"`

}

By chaining these vulnerabilities, an attacker can circumvent the limitations placed on the number of login attempts.

PoC

1. Run the provided PoC script.
2. Observe that the script makes 6 login attempts, one more than the set limit of 5 failed attempts.
3. This is made possible because the script triggers a server restart via the DoS vulnerability after 5 failed attempts, thus resetting the counter for failed login attempts.

Impact

This is a critical security vulnerability that allows attackers to bypass the brute force login protection mechanism. Not only can they crash the service affecting all users, but they can also make unlimited login attempts, increasing the risk of account compromise.

Argo CD is a declarative, GitOps continuous delivery tool for Kubernetes. Prior to versions 2.8.13, 2.9.9, and 2.10.4, an attacker can exploit a chain of vulnerabilities, including a Denial of Service (DoS) flaw and in-memory data storage weakness, to effectively bypass the application's brute force login protection. This is a critical security vulnerability that allows attackers to bypass the brute force login protection mechanism. Not only can they crash the service affecting all users, but they can also make unlimited login attempts, increasing the risk of account compromise. Versions 2.8.13, 2.9.9, and 2.10.4 contain a patch for this issue.

Argo CD is a declarative, GitOps continuous delivery tool for Kubernetes. Prior to versions 2.8.13, 2.9.9, and 2.10.4, an attacker can effectively bypass the rate limit and brute force protections by exploiting the application's weak cache-based mechanism. This loophole in security can be combined with other vulnerabilities to attack the default admin account. This flaw undermines a patch for CVE-2020-8827 intended to protect against brute-force attacks. The application's brute force protection relies on a cache mechanism that tracks login attempts for each user. This cache is limited to a defaultMaxCacheSize of 1000 entries. An attacker can overflow this cache by bombarding it with login attempts for different users, thereby pushing out the admin account's failed attempts and effectively resetting the rate limit for that account. This is a severe vulnerability that enables attackers to perform brute force attacks at an accelerated rate, especially targeting the default admin account. Users should upgrade to version 2.8.13, 2.9.9, or 2.10.4 to receive a patch.

An attacker can effectively bypass the rate limit and brute force protections in Argo CD by exploiting the application's weak cache-based mechanism. The application's brute force protection relies on a cache mechanism that tracks login attempts for each user. An attacker can overflow this cache by bombarding it with login attempts for different users, thereby pushing out the admin account's failed attempts and effectively resetting the rate limit for that account.