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    Penetration Tester

    Technology
    Claranet Limited
    London
    Permanent
    Competitive
    On-Site

    Job Description

    Essential Roles & Responsibilities

    As a Penetration Tester at Claranet, you will able to deliver you own web application tests and through training and partnering, you will be involved in a full range of testing work from mobile app and infrastructure testing to social engineering and Red Team exercises.

    Key Responsibilities:

    • Undertaking web and mobile application testing and infrastructure testing engagements

    • Using the opportunities provided by the business to improve skills and capabilities into all areas of testing

    • Working with key clients providing bespoke consultancy, analysis and expertise

    • Collaborating with other Claranet Business Units on large client digital transformation projects

    • Assisting with pre/post sales activities as required

    • Encouraging a positive, proactive, collaborative and solution-oriented approach among colleagues

    • Communicating within Claranet and with clients, both orally and in writing

    • Contribute to the writing and publishing of whitepapers and advisories

    • Developing and delivering webinar content

    • Delivering targeted research and development in line with direction of the business

    • If not achieved already, working towards CREST qualifications; CPSA, CRT and CCT Essential Technical:

    • Have a good understanding of web & mobile application and infrastructure testing and methodologies

    • Able to manually and proficiently exploit web application and network infrastructure vulnerabilities

    • Have a logical and time-conscious approach to report writing

    • Have a working knowledge of common programming languages such as C, C++, C#, Java

    • Have experience of at least one scripting language such as Ruby, Python or Perl Essential Experience:

    • Delivering chargeable web app testing engagements

    • Providing remediation advice

    • Producing accurate technical reports

    • Working under pressure of deadlines and structuring workload accordingly

    • Problem-solving, helping others to understand complex ideas Essential General:

    • Client facing, able to confidently and professionally represent the company

    • Must be self-motivated and able to work in an independent manner as well as part of a team

    • Excellent written and oral communications skills

    • Positive, collaborative and enthusiastic

    • Conducting penetration testing work out of normal office hours on occasion

    • Willing to travel to deliver onsite work as required

    • Appetite to shadow, train and develop to improve capabilities into all areas of security testing In Addition, The Following Are Highly Desirable:

    • Security clearance (or eligibility for clearance)

    • CTM or CTL status

    • CISSP, CISA, CEH, OSCP or equivalent reputable information security certifications

    • Familiarity with testing cloud environments

    • Public speaking experience

    • Full UK driving license

    Posted on August 12, 2026

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