An unsigned timestamp can leave a SOAP message open to tampering and replay attacks.
A Security timestamp indicates a message's freshness. If an attacker intercepts a message retransmits it at a later time, the receiver can reject the replay attack because the timestamp will indicate that the message is stale. Optionally, timestamps can include an expiration attribute which places a hard limit on how long security semantics are valid.
To prevent attackers from tampering with timestamps, timestamps should be signed. Without a signed timestamp, an attacker can intercept a SOAP message, modify the timestamp, and send the message on without the receiver's knowledge. Under these circumstances, an attacker can potentially trick a recipient into accepting a malicious message.
The following client configuration tells WebSphere to send unsigned timestamps:
<com.ibm.etools.webservice.wscext:WsClientExtension xmi:version="2.0" xmlns:xmi="http://www.omg.org/XMI" xmlns:com.ibm.etools.webservice.wscext="http://www.ibm.com/websphere/appserver/schemas/5.0.2/wscext.xmi" xmi:id="WsClientExtension_1152150778436">
...
<securityRequestGeneratorServiceConfig xmi:id="SecurityRequestGeneratorServiceConfig_1212078169562">
<addTimestamp xmi:id="AddTimestamp_1212093882250"/>
...
</com.ibm.etools.webservice.wscext:WsClientExtension>
[1] Standards Mapping - OWASP Top 10 2004 - (OWASP 2004) A10 Insecure Configuration Management
[2] Standards Mapping - OWASP Top 10 2010 - (OWASP 2010) A6 Security Misconfiguration
[3] Standards Mapping - FIPS200 - (FISMA) CM
[4] Standards Mapping - Common Weakness Enumeration - (CWE) CWE ID 345
[5] Standards Mapping - Web Application Security Consortium 24 + 2 - (WASC 24 + 2) Insufficient Authentication
[6] Standards Mapping - Payment Card Industry Data Security Standard Version 1.1 - (PCI 1.1) Requirement 6.5.10
[7] Web Sericces Security: SOAP Message Security 1.1 OASIS
[8] Web Services Handbook for WebSphere Application Server 6.1 IBM Redbooks