Published: 07 June 2021

We've previously written about many different techniques for Finding and Exploiting SQL Injection vulnerabilities. However, there are often restrictions and interim technologies such as Web Application Firewalls that can prevent certain payloads from being used. In some instances filters can be bypassed through common encoding mechanisms, however often these will be ineffective and other methods much be used.

Published: 07 June 2021

Command Injection vulnerabilities occur where user supplied input is insecurely included within an operating system command, allowing an attacker to execute additional commands or alter the syntax of the executed command. This vulnerability typically allows for confidential data theft and may allow a threat actor to target internal network connections for further attacks.

Published: 07 June 2021

Weak passwords are those which are predictable and can be easily guessed. To ensure that users do not select weak passwords organisations may look to enforce password complexity. Complexity refers to the requirement to use a mixed character set. For example, on Active Directory accounts complexity requires three of the four: uppercase, lowercase, numbers, and symbols. However it is still possible to select weak passwords with complexity enabled, such as `Welcome!`, `Summer2020`, or `Password123456`.

Published: 31 May 2021

Hosting web application content such as dynamic scripts and stylesheets on third parties such as Content Delivery Networks (CDNs) can allow for significant improvements to site performance and can reduce bandwidth costs. However, scripts included within a web application will execute within the user's browser with the same privileges as the currently logged in user. Therefore if a script is included from an external domain, that domain is trusted with the confidentiality and integrity of data stored within the application.

Published: 14 April 2021

Certification Authority Authorization (CAA) is a used to specify which Certificate Authorities may issue certificates for the domain. Whilst lack of CAA does not constitute a vulnerability itself, it may be used to harden the transport layer security of an application by reducing the risk of certificates being mis-issued. Additionally, it can be used to notify the application owner when a mis-issue is detected and prevented through CAA.

Published: 10 March 2021

Major outages in major public cloud providers such as Azure and AWS are rare, but they do happen. Today OVH had a major incident: “OVH datacenter burns down knocking major sites offline” and they’re not the only ones to experience these issues, for example Amazon had a major outage in November and Microsoft had one in September.

This prompted me to write up an article on Akimbo’s recent work building resilience into our platform, so today I’m going to talk a little bit about a couple of the features of AWS that allow for significant resilience and I’m going to do that by running you through my recent experiments on our platform which can be roughly summarised as “Turning things off to see what breaks.”

Published: 26 January 2021

Out-of-band exploitation refers to exploits where the extracted information is received over a connection other than the one the payload was delivered over. It can be used to bypass defensive technologies as well as complicating the detection and response capability. SQL Injection can be exploited out-of-band through protocols such as DNS in order to extract database contents. This is particularly useful as an alternative to Time-based exploitation where it can allow for faster extraction. If you're new to this vulnerability, it's worth starting at SQL Injection  basics first, before reading this article.

The idea behind out-of-band exploitation is fairly simple, instead of inferring content in the database through something like Boolean logic, you can request the target system transmit the information over protocols such as HTTP, SMB or DNS.

Published: 23 January 2021

When performing security tests, we very often come across weak passwords. We often see dictionary words with suffixes such as Welcome1, Password123, or Lockdown2020. We also see "leet" substitutions, such as P@55w0rd, 3l3ph@nt, or L0ckd0wn. We've previously shown how quickly password cracking can be performed. With passwords like the above they would be cracked easily. Simple protections such as "Password complexity" don't solve the problem on their own, for example complexity enforces the requirement for three of the following: uppercase, lowercase, numbers, and symbols - which all of the weak options above meet.

Published: 23 January 2021

In a previous article we discussed how bruteforcing Windows accounts is often easier than people expect. In this post - we'll cover some steps to harden these accounts.

The Observation Window

When configuring an account lockout threshold on a Domain another setting is suggested, the observation window. This setting effectively reduces the protection of the account lockout by setting a timer. For example, a lockout threshold of 5 and an observation window of 30 minutes has the impact of meaning that if an attacker attempts 5 incorrect passwords within 30 minutes the account will lock - but four passwords would not cause it to lock.

Therefore, an attacker could attempt 4 passwords every 30 minutes - or 192 per account per day, without locking any accounts.

Published: 23 January 2021

We recently discussed how to break WPA2 keys very quickly using cloud computing. We've also looked at how to use a Rogue AP to capture user credentials from a network using PEAP (MSCHAP).

In this article we'll look at hardening Enterprise wireless networks from these attacks.

The most secure option is to utilise mutual authentication (where both the server and the client authenticate to each other) using digital certificate based authentication, such as offered by EAP-TLS. However, there can be more administrative overhead involved in the deployment of these networks and therefore PEAP may be offer a balance of security and overhead.

To be clear, we recommend the use of EAP-TLS wherever possible - but if you must use PEAP, we offer the following hardening steps:

Published: 22 January 2021

SQL Injection is a vulnerability that occurs where user supplied input is insecurely concatenated into an SQL query. We showed how easy can be to detect in our Finding SQL Injection article, and we’ve run through exploitation in many posts such as our post on Exploiting Error-based SQL Injection.

However, in this post, we’re looking at fixing it. The fix is quite a simple code change. As the issue described is user input insecurely concatenated into a query, the remediation for SQL injection is fairly simple: don’t build queries through string concatenation. Instead, it’s more secure to use “Prepared Statements”, often called “Parameterized Queries”. All modern languages support this type of query either directly or through a framework; here we will supply a PHP example to show the difference.

Published: 21 January 2021

In our article LLMNR and NetBIOS-NS Spoofing with Responder we stepped you through how to exploit a very common issue on Windows networks. In this one, we’re going to cover how to fix it.

Link-Local Multicast Name Resolution (LLMNR) and NetBIOS-Name Service (NBT-NS) are name resolution protocols that are enabled by default on Windows machines. They’re both used as a fallback for DNS. If a machine requests a hostname, such as when attempting to connect to a file-share, and the DNS server doesn’t have an answer – either because the DNS server is temporarily unavailable or the hostname was incorrectly typed – then an LLMNR request will be sent, followed by an NBT request. LLMNR is a multicast protocol and NBT-NS is a broadcast protocol.

Published: 25 October 2020

Whilst Reflected and Stored XSS can generally be addressed through server-side user input encoding (such as through the PHP htmlentities() function) or with browser protections such as Content-Security-Policy – this is not sufficient for DOM-XSS.

Where a dangerous function is used, user input into that function should be limited through user input filtering. An allow-list approach of restricting user input to only known-good input should be used. For example, limiting input to the smallest number of characters possible (such as alphanumerics only) and checking the expected data type (such as limiting input to integers only). This is in contrast to a block-list of known-bad inputs being blocked, which is often less effective due to the large degree of flexibility that JavaScript allows. For a good example of this flexibility, consider something like JScrewIt.

Published: 25 October 2020

This issue comes about where user supplied input is included within server responses without filtration or encoding.

One very effective method of preventing this attack is to use an allow-list (sometimes called a whitelist) which will allow only known good content. For example if your expected input is an integer and the user supplies anything other than an integer you can simply reject that input – and perhaps supply a message to inform the user what the issue is, without including the original payload.

Published: 19 October 2020

We covered extracting domain hashes with Mimikatz previously, but that's not always the best approach - for example where anti-virus is getting in the way. However there are other options for the same goal. This time around we'll take a look at using Vssadmin, a built-in Windows tool. VSSAdmin is the Volume Shadow Copy Administrative  command-line tool and it can be used to take a copy of the NTDS.dit file - the file that contains the active directory domain hashes.