The Criminal Justice Secure eMail system (CJSM) relies on insecure protocols that some security conscious organisations deliberately block, claims a Register source.
CJSM is run by Vodafone on behalf of the government and designed to provide secure communications between the GSI (Government Secure Intranet) and external organisations in the criminal justice field, such as solicitors and police contractors.
Security problems with the system came to El Reg’s attention following a tip-off from a reader, who works for a firm that supplies internet services to several UK police forces.
“Their webmail site (www.cjsm.net) recently started being blocked by our web security proxy, and on investigation it turns out their site supports only one cypher for https RC4,” our tipster told us.
"As a contractor for various police forces we are contractually obliged to use CJSM for 'secure' communications and therefore are forced to continue using this insecure protocol," the tipster added.
This is a problem because RC4 is hopelessly outdated and insecure. Microsoft has recommended against the use of RC4 since November 2013, and RFC7465 has prohibited its use since February. The latest research into the shortcomings of RC4 casts the technology in an even less favourable light.
RC4 was designed in the 1980s and remains a widely used stream cipher despite increasing doubts about its robustness to attack from well-motivated and well-funded adversaries – for example, global intelligence agencies. Breaking into the secure web mail system is well beyond the capability of cybercrooks, but well within the potential capability of any tier-1 intel agency.
SSL Labs scores the CJSM site with an F. The poor grade arises because the site was vulnerable to the CVE-2014-0224 bug, a flaw that gives an active network attacker a way to hijack a victim's connection to the vulnerable server.
Other than that, the site seems poorly configured, offering only the insecure RC4-based suite, a third-party expert told El Reg, confirming our tipster's criticism. Other major sites continue to offer RC4, but only as a last resort, after attempts to negotiate the better encryption supporting modern clients have failed.
El Reg put these criticisms to Vodafone, which forwarded our query to the UK's Ministry of Justice. In response, the MoJ downplayed immediate security concerns while stating that an unspecified upgrade is in the works.
The email system used by our criminal justice agencies to share information is secure and encrypted.
As security is paramount we always look for ways to improve systems, which is why we are carrying out further upgrade work.
In the meantime, the system remains secure, and users can send information as normal.
Our tipster was unimpressed by this response, characterising it as PR-driven.
"Someone isn’t on the ball with security," our source said. "I’m no crypto expert but tools like SSL Labs make it very easy to test your site’s security and anyone with a passing interest in network security should know RC4 is bad news."
"For this to be the only option for connecting to CJSM more than 18 months after Microsoft advised everyone to disable RC4 is pretty inexcusable," the source added.
Government systems are periodically subject to security audits and penetration tests, so the issues with the CJSM system ought to have been picked up by a vulnerability scan. This makes the lack of action so far a puzzle. Our understanding here at The Register is that an upgrade would not be particularly difficult nor expensive.
"Whilst RC4 can be cracked, it still isn’t easy and requires analysis of a considerable volume of data, so maybe it’s a bit secure," our source concluded. "But to me the point is they are not following industry advice and it’s not as secure as it ought to be. More worrying, I’ve had to weaken our security to accommodate them." ®