Hello Everyone, I will keep it short and simple :p

Step 1: Upload the Provided File on Virus Total for Analysis

Step 2: Go to Cryptographic Plain Text in the Behaviour Section

You will have the following:

Cryptographical plain text

5481237002
7267561120:QkhGbGFnWXt0M2xlZ3I0bV9nMGVzX3chbGR9

Step 3: Copy the Token which is QkhGbGFnWXt0M2xlZ3I0bV9nMGVzX3chbGR9

Step 4: Paste the Token in Input section of Cyberchef having the URL https://gchq.github.io/CyberChef/

Step 5: Use the Function "Decode from Base64"

Step 6: You will receive the following Flag:

BHFlagY{t3legr4m_g0es_w!ld}

Have Fun!