In this excerpt of a Trend Micro Vulnerability Research Service vulnerability report, Justin Hung and Dusan Stevanovic of the Trend Micro Research Team detail a recently patched SQL injection vulnerability in Zoho ManageEngine products. The bug is due to improper validation of resource types in the AutoLogonHelperUtil class. Successful exploitation of this vulnerability could lead to arbitrary SQL code execution in the security context of the database service, which runs with SYSTEM privileges. The following is a portion of their write-up covering CVE-2022-3236, with a few minimal modifications.

ManageEngine recently patched a SQL injection vulnerability bug in their Password Manager Pro, PAM360, and Access Manager Plus products. The vulnerability is due to improper validation of resource types in the AutoLogonHelperUtil class. A remote attacker can exploit the vulnerability by sending a crafted request to the target server. Successful exploitation could lead to arbitrary SQL code execution in the security context of the database service, which runs with SYSTEM privileges.

The Vulnerability

Password Manager Pro is a secure vault for storing and managing shared sensitive information such as passwords, documents, and digital identities of enterprises. The product is also included in other two similar ManageEngine products: PAM360 and Access Manager Plus. A user can access the web console on these products through HTTPS requests via the following ports:

The HTTP request body may contain data of various types. The data type is indicated in the Content-Type header field. One of the standardized types is multipart, which contains various subtypes that share a common syntax. The most widely used subtype of multipart type is multipart/form-data. Multipart/form-data is made up of multiple parts, each of which contains a Content-Disposition header. Each part is separated by a string of characters. The string of characters separating the parts is defined by the boundary keyword found in the Content-Type header line. The Content-Disposition header contains parameters in “name=value” format. Additional header lines may be present in each part; each header line is separated by a CRLF sequence. The last header line is terminated by two consecutive CRLFs sequences and the form element’s data follows. The filename parameter in a ContentDisposition header provides a suggested file name to be used if the element's data is detached and stored in a separate file.

A user with admin privileges can add/edit a resource type via Password Manager Pro web interface by clicking the menu “Resources” -> “Resource Types” -> “Add” (or “Edit”) and a HTTP multipart/form-data request will be submitted to the “AddResourceType.ve” endpoint, as an example shown below:

where several form-data parts are transferred in the request, like “TYPEID”, “dnsname_label”, “resLabChkName__1”, etc. The data carried in the multipart/form-data part with a name parameter value of “resourceType” represents the name of the resource type, which is relevant to the vulnerability in this report.

An SQL injection vulnerability exists in Password Manager Pro. The vulnerability is due to a lack of sanitization of the name of the resource type in the Java class AutoLogonHelperUtil. The AutoLogonHelperUtil class is used by several controller classes, like AutologonController and PasswordViewController, to construct a partial SQL statement related to the query for existing resource types. For example, if a user clicks the menu “Connections” on the web admin interface, a request will be sent to “AutoLogonPasswords.ec” endpoint, and the includeView() method of ViewProcessorServlet class is called. The includeView() method will use AutologonController class to handle the request. The AutologonController class is derived from the SqlViewController class and its updateViewModel() method is called to process the request. The updateViewModel() method will first call the initializeSQL() method to get an SQL statement. It then calls the getAsTableModel() method of the SQLQueryAPI class to execute the SQL statement.

In the initializeSQL() method, it will call the getSQLString() method of the AutologonController class to get the SQL statement, which will invoke the getFilledString() method of the TemplateAPI class. In the getFilledString() method, it will call the getVariableValue() method of the AutologonController. The getVariableValue() method will use the getOSTypeCriteriaForView() method of the AutoLogonHelperUtil class to construct a partial SQL statement. The getOSTypeCriteriaForView() will call the getOSTypeCriteria() method, which uses getOSTypeList() to read all resource types from the database. It then uses these resource types to build a partial SQL statement as below:

where <resource type n> represents a resource type name queried from a database by the getOSTypeList() method. Then, this partial SQL statement will be returned to getOSTypeCriteriaForView() and then be returned to the getFilledString(). The getFilledString() will use this partial SQL statement to generate the final complete SQL statement and return it back to getSQLString().

However, the getOSTypeCriteria() method of the AutoLogonHelperUtil class does not sanitize the name of the resource type (returned from getOSTypeList()) for SQL injection characters before using it to create a partial SQL statement. An attacker can therefore first add a new resource type (or edit an existing resource type) with a crafted resource type name containing a malicious SQL command, and then click a menu such as “Connections” to invoke the methods of the AutoLogonHelperUtil class which will use the malicious resource type name to construct a SQL statement. This could trigger the execution of the injected SQL command.

A remote authenticated attacker can exploit the vulnerability by sending a crafted request to the target server. Successful exploitation could lead to arbitrary SQL code execution in the security context of the database service, which runs with SYSTEM privileges.

Detection Guidance

To detect an attack exploiting this vulnerability, the detection device must monitor and parse traffic on the ports listed above. Note that the traffic is encrypted via HTTPS and should be decrypted before performing the following steps.

The detection device must inspect HTTP POST requests to a Request-URI containing the following string:

        /AddResourceType.ve

If found, the detection device must inspect each part of the multipart/form-data parts in the body of the request. In each part, the detection device must search for the Content-Disposition header and its name parameter to see if its value is “resourceType”. If found, the detection device must continue to inspect the data carried in this multipart/ form-data part to see if it contains the single-quote character “' (\x27)”. If found, the traffic should be considered malicious and an attack exploiting this vulnerability is likely underway. An example of malicious requests is shown below:

Additional notes:

• The string matching for the Request-URI and “POST” should be performed in a case-sensitive manner, while other string matching like “name”, “resourceType” and “Content-Disposition” should be performed in a case-insensitive manner.
• The Request-URI may be URL encoded and should be decoded before applying the detection guidance.
• It is possible that the single quote “' (\x27)” is naturally found in the resource type name resulting in false positives. However, in normal cases, the possibility should be low.

Conclusion

ManageEngine patched this and other SQL injections in September. Interestingly, the patch for PAM360 came a day after the patches for Password Manager Pro and Access Manager Plus. The vendor offers no other workarounds. Applying these updates is the only way to fully protect yourself from these bugs.

Special thanks to Justin Hung and Dusan Stevanovic of the Trend Micro Research Team for providing such a thorough analysis of this vulnerability. For an overview of Trend Micro Research services please visit http://go.trendmicro.com/tis/.

The threat research team will be back with other great vulnerability analysis reports in the future. Until then, follow the team on Twitter, Mastodon, LinkedIn, or Instagram for the latest in exploit techniques and security patches.