CWE-252: Unchecked Return Value

Description

The product does not check the return value from a method or function, which can prevent it from detecting unexpected states and conditions.

Two common programmer assumptions are "this function call can never fail" and "it doesn't matter if this function call fails". If an attacker can force the function to fail or otherwise return a value that is not expected, then the subsequent program logic could lead to a vulnerability, because the product is not in a state that the programmer assumes. For example, if the program calls a function to drop privileges but does not check the return code to ensure that privileges were successfully dropped, then the program will continue to operate with the higher privileges.

Potential Impact

Demonstrative Examples

char buf[10], cp_buf[10];fgets(buf, 10, stdin);strcpy(cp_buf, buf);

int returnChunkSize(void *) {
                        
                           
                           /* if chunk info is valid, return the size of usable memory,
                           
                           
                           * else, return -1 to indicate an error
                           
                           
                           */
                           ...
                     }int main() {...memcpy(destBuf, srcBuf, (returnChunkSize(destBuf)-1));...}

buf = (char*) malloc(req_size);strncpy(buf, xfer, req_size);

char[] byteArray = new char[1024];for (IEnumerator i=users.GetEnumerator(); i.MoveNext() ;i.Current()) {String userName = (String) i.Current();String pFileName = PFILE_ROOT + "/" + userName;StreamReader sr = new StreamReader(pFileName);sr.Read(byteArray,0,1024);//the file is always 1k bytessr.Close();processPFile(userName, byteArray);}

FileInputStream fis;byte[] byteArray = new byte[1024];for (Iterator i=users.iterator(); i.hasNext();) {
                        String userName = (String) i.next();String pFileName = PFILE_ROOT + "/" + userName;FileInputStream fis = new FileInputStream(pFileName);fis.read(byteArray); // the file is always 1k bytesfis.close();processPFile(userName, byteArray);

Mitigations & Prevention

Detection Methods

• Automated Static Analysis High — Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then sea

Real-World CVE Examples

Related Weaknesses

Taxonomy Mappings

• 7 Pernicious Kingdoms: — Unchecked Return Value
• CLASP: — Ignored function return value
• OWASP Top Ten 2004: A7 — Improper Error Handling
• CERT C Secure Coding: ERR33-C — Detect and handle standard library errors
• CERT C Secure Coding: POS54-C — Detect and handle POSIX library errors
• The CERT Oracle Secure Coding Standard for Java (2011): EXP00-J — Do not ignore values returned by methods
• SEI CERT Perl Coding Standard: EXP32-PL — Do not ignore function return values
• Software Fault Patterns: SFP4 — Unchecked Status Condition
• OMG ASCSM: ASCSM-CWE-252-resource —
• OMG ASCRM: ASCRM-CWE-252-data —
• OMG ASCRM: ASCRM-CWE-252-resource —